diff --git a/M02_MasterTemplete/M02_Library_Same_Router.py b/M02_MasterTemplete/M02_Library_Same_Router.py
new file mode 100644
index 000000000..0d0012d16
--- /dev/null
+++ b/M02_MasterTemplete/M02_Library_Same_Router.py
@@ -0,0 +1,352 @@
+"""M02 서고 [중복 찾기] · 합치기 · 되돌림(PLAN 733-3 · 요구서_572 3장 4 · 분석 D-3) —
+단가산출(`sangeun` SK) · 일위대가(`precombo` SC).
+
+GET  /layers/{층}/{kind}-same — 이 층 + 위 층(회사 · 마스터) 같은 지문 묶음(이 층 문서가 든
+     묶음만) · 문서마다 층 · 키 · 이름 · 구분 · 쓰는 곳 수 · 꼬리표 「내용 같음」 ·
+     SC 「수량만 다름」(`본뜬.실무수량` 다름) · 합친 것 목록(되돌림)
+POST …/merge {남김, 지움[], 판} — 서버가 지문 다시 셈(다르면 409) · 쓰는 곳 참조를 남김으로
+     (쓰기 권한 닿는 곳만 · `store.write` 정본 다시 셈) · 남은 쓰는 곳이 있는 문서 = 안 지움
+     「남김 — 쓰는 곳 N」 · 나머지 = `{층}/_합친것/<키>.json` 으로 옮김 · 나무 자리 걷음
+POST …/undo {키} — `_합친것/` 에서 되돌림 · 옮긴 참조도 되돌림
+지움 = 이 층 문서만 · 남김 = 이 층 또는 위 층(위 층과 같은 아래 층 문서 = 남김 = 위 층 키) ·
+판 = 이 층 서고 나무 판(`{종류}_폴더.json`) · 권한 = 그 층 쓰기 · 프로젝트 사본 = 굳힌 값이라
+안 건드림 · 지문 = `M02_Library_Same`(733-1) 읽기만.
+⚠ 등록은 `main.py`(로그인만).
+"""
+
+from __future__ import annotations
+
+import json
+from datetime import datetime
+from pathlib import Path
+from typing import Any, Literal
+
+from fastapi import APIRouter, Depends, HTTPException
+from pydantic import BaseModel
+
+from common_util.common_util_auth import verify_session
+from common_util.common_util_json import atomic_write_json
+from M02_MasterTemplete import M02_Labor_Ref as refs
+from M02_MasterTemplete import M02_Layer_Access as access
+from M02_MasterTemplete import M02_Library_Same as same
+from M02_MasterTemplete import M02_MasterTemplete_Store as store
+from M02_MasterTemplete import M02_Precombo_Folders as pre_folders
+from M02_MasterTemplete import M02_Template_Layers as layers
+from M02_MasterTemplete.M02_MasterTemplete_Router_Items import Layer, Session, _root
+
+router = APIRouter(prefix="/api/m02", tags=["M02 MasterTemplete Library Same"])
+
+Kind = Literal["precombo", "sangeun"]
+GONE = "_합친것"
+USER_KINDS = (("labor", "구조물 조합"), ("precombo", "일위대가"), ("sangeun", "단가산출"))
+_ORDER = {"system": 0, "company": 1, "personal": 2}
+
+
+class MergeBody(BaseModel):
+    """`남김` = {층, 주인, 키}(이 층 · 위 층) · `지움` = 이 층 키들 · `판` = 이 층 서고 나무 판."""
+
+    남김: dict[str, Any]
+    지움: list[str]
+    판: str
+
+
+class UndoBody(BaseModel):
+    키: str
+
+
+def _bad(status: int, text: Any) -> store.StoreError:
+    return store.StoreError(status, text)
+
+
+def _ref(at: refs.Here, key: str) -> refs.Ref:
+    return {"층": at[0], "주인": at[1], "키": key}
+
+
+def _uppers(at: refs.Here) -> list[refs.Here]:
+    """이 층이 읽는 위 층 — 개인 → 그 회사 · 마스터 / 회사 → 마스터 / 마스터 → 없음."""
+    layer, owner = at
+    if layer == "personal":
+        return [("company", str(owner).split("/")[0]), ("system", None)]
+    return [("system", None)] if layer == "company" else []
+
+
+def _docs(at: refs.Here, kind: str) -> list[tuple[str, dict[str, Any]]]:
+    folder = refs.folder_of(*at) / kind
+    out = []
+    for path in sorted(folder.glob("[!._]*.json")) if folder.is_dir() else []:
+        try:
+            doc = json.loads(path.read_bytes())
+        except (OSError, ValueError):
+            continue
+        if isinstance(doc, dict):
+            out.append((path.stem, doc))
+    return out
+
+
+def _finger(at: refs.Here, kind: str, doc: dict[str, Any]) -> str | None:
+    """문서 내용 지문(733-1 · 빈 문서 None) — 참조는 가리킨 문서 지문(층 넘어 사본도 같음)."""
+    with store.at(refs.folder_of(*at)):
+        return same.finger(kind, doc)
+
+
+# ── 쓰는 곳 ───────────────────────────────────────────────────────────
+def _user_index() -> dict[str, list[tuple[Path, str, str]]]:
+    """모든 층(프로젝트 뺌) 훑기 한 번 — {ref_id: [(파일, 종류, 「어디 이름」)]}."""
+    out: dict[str, list[tuple[Path, str, str]]] = {}
+    for kind, what in USER_KINDS:
+        for where, path in layers.layer_files(kind):
+            try:
+                doc = json.loads(path.read_bytes())
+            except (OSError, ValueError):
+                continue
+            name = doc.get("일위대가번") or doc.get("이름") or path.stem
+            for rid in {refs.ref_id(one) for one in refs.refs_in(doc)}:
+                out.setdefault(rid, []).append((path, kind, f"{what} {where} 「{name}」"))
+    return out
+
+
+def _can_write(session: Session, at: refs.Here) -> bool:
+    try:
+        return access.grant(session, at[0], at[1]).write
+    except HTTPException:
+        return False
+
+
+def _retarget(doc: dict[str, Any], olds: set[str], new: refs.Ref) -> dict[str, Any]:
+    """문서의 `olds` 참조를 모두 `new` 로(규격 열 수량 열쇠까지 · `M02_Labor_Ref` 한 벌)."""
+    done: dict[str, refs.Ref] = {}
+
+    def move(ref: refs.Ref, _depth: int) -> refs.Ref:
+        if refs.ref_id(ref) in olds:
+            done[refs.ref_id(ref)] = new
+            return new
+        return ref
+
+    return refs._spec_moved(refs._move_doc(doc, move, 1), done)
+
+
+def _rewrite(path: Path, kind: str, olds: set[str], new: refs.Ref) -> None:
+    """쓰는 곳 한 파일 — 참조를 바꿔 `store.write`(서버 정본 다시 셈 · 판 검사)."""
+    raw = path.read_bytes()
+    doc = _retarget(json.loads(raw), olds, new)
+    with store.at(path.parent.parent):
+        store.write(kind, path.stem, store.version_of(raw), doc)
+
+
+# ── 목록 ──────────────────────────────────────────────────────────────
+def _qty(doc: dict[str, Any]) -> str:
+    return json.dumps((doc.get("본뜬") or {}).get("실무수량") or {}, sort_keys=True)
+
+
+def _row(at: refs.Here, key: str, doc: dict[str, Any], used: int, mine: refs.Here) -> dict:
+    return {
+        "층": at[0],
+        "주인": at[1],
+        "키": key,
+        "이름": doc.get("이름") or key,
+        "구분": doc.get("구분") or "",
+        "상세구분": doc.get("상세구분") or "",
+        "쓰는곳수": used,
+        "위층": at != mine,
+    }
+
+
+def _gone_rows(folder: Path, kind: str) -> list[dict[str, Any]]:
+    out = []
+    for path in sorted((folder / GONE).glob("*.json")):
+        try:
+            rec = json.loads(path.read_bytes())
+        except (OSError, ValueError):
+            continue
+        if rec.get("종류") == kind:
+            doc = rec.get("문서") or {}
+            out.append(
+                {
+                    "키": rec.get("키"),
+                    "이름": doc.get("이름") or rec.get("키"),
+                    "남김": rec.get("남김"),
+                    "때": rec.get("때"),
+                    "옮긴곳수": len(rec.get("옮긴곳") or []),
+                }
+            )
+    return out
+
+
+def find(folder: Path, kind: str) -> dict[str, Any]:
+    """이 층 + 위 층 같은 지문 묶음 — 이 층 문서가 든 묶음 · 둘 이상만."""
+    mine = refs.where(folder)
+    index = _user_index()
+    groups: dict[str, list[tuple[refs.Here, str, dict[str, Any]]]] = {}
+    for at in [mine, *_uppers(mine)]:
+        for key, doc in _docs(at, kind):
+            if (mark := _finger(at, kind, doc)) is not None:
+                groups.setdefault(mark, []).append((at, key, doc))
+    out = []
+    for mark, docs in groups.items():
+        if len(docs) < 2 or all(at != mine for at, _, _ in docs):
+            continue
+        docs.sort(key=lambda d: (_ORDER[d[0][0]], d[1]))
+        rows = [
+            _row(at, key, doc, len(index.get(refs.ref_id(_ref(at, key)), [])), mine)
+            for at, key, doc in docs
+        ]
+        qty = kind == "precombo" and len({_qty(doc) for _, _, doc in docs}) > 1
+        out.append({"지문": mark, "꼬리표": "수량만 다름" if qty else "내용 같음", "문서": rows})
+    out.sort(key=lambda g: (g["꼬리표"] != "내용 같음", g["문서"][0]["이름"]))
+    with store.at(folder):
+        판 = pre_folders.view(kind)["판"]
+    return {"판": 판, "묶음": out, "합친것": _gone_rows(folder, kind)}
+
+
+# ── 합치기 ────────────────────────────────────────────────────────────
+def merge(session: Session, folder: Path, kind: str, body: MergeBody) -> dict[str, Any]:
+    mine = refs.where(folder)
+    raw = body.남김 or {}
+    keep_at: refs.Here = (str(raw.get("층") or ""), raw.get("주인") or None)
+    keep = _ref(keep_at, str(raw.get("키") or ""))
+    if keep_at not in [mine, *_uppers(mine)]:
+        raise _bad(400, "남김은 이 층 또는 위 층 문서")
+    if refs.kind_of(keep["키"]) != kind or (keep_doc := refs.read_ref(keep)) is None:
+        raise _bad(404, f"없는 {refs.TITLE[kind]} 「{keep['키']}」")
+    gone = list(dict.fromkeys(str(k) for k in body.지움))
+    if not gone or (keep_at == mine and keep["키"] in gone):
+        raise _bad(400, "지울 문서를 고름 — 남김과 달라야 함")
+    have = dict(_docs(mine, kind))
+    if miss := [k for k in gone if k not in have]:
+        raise _bad(404, f"이 층에 없는 문서 「{' · '.join(miss)}」")
+    with store.at(folder):
+        tree_doc, 판 = pre_folders._read(kind)
+    if 판 != body.판:
+        raise _bad(409, {"stale": [pre_folders.file_of(kind)], "판": 판})
+    mark = _finger(keep_at, kind, keep_doc)
+    if mark is None or any(_finger(mine, kind, have[k]) != mark for k in gone):
+        raise _bad(409, "내용이 그새 달라짐 — [중복 찾기]를 다시 누름")
+
+    rids = {refs.ref_id(_ref(mine, k)): k for k in gone}
+    by_file: dict[Path, tuple[str, set[str]]] = {}
+    labels: dict[Path, str] = {}
+    index = _user_index()
+    for rid in rids:
+        for path, ukind, label in index.get(rid, []):
+            by_file.setdefault(path, (ukind, set()))[1].add(rid)
+            labels[path] = label
+    moved: dict[str, list[dict[str, Any]]] = {k: [] for k in gone}
+    left: dict[str, list[str]] = {k: [] for k in gone}
+    for path, (ukind, olds) in by_file.items():
+        at = refs.where(path.parent.parent)
+        why = ""
+        if not (_can_write(session, at) and refs.readable(at, keep)):
+            why = "권한 밖"
+        else:
+            try:
+                _rewrite(path, ukind, olds, keep)
+            except store.StoreError as error:  # 같은 참조 두 번 등 — 그 쓰는 곳은 그대로 둠
+                why = str(error.detail)
+        for rid in olds:
+            if why:
+                left[rids[rid]].append(f"{labels[path]} — {why}")
+            else:
+                moved[rids[rid]].append(
+                    {"층": at[0], "주인": at[1], "종류": ukind, "이름": path.stem}
+                )
+
+    places = dict(tree_doc.get("자리") or {})
+    done, kept = [], []
+    when = datetime.now().isoformat(timespec="seconds")
+    # ponytail: 여러 파일을 차례로 씀(잠금 없음) — 동시에 같은 층을 합치면 앞 것이 이김
+    for key in gone:
+        if left[key]:
+            kept.append({"키": key, "쓰는곳": left[key]})
+            continue
+        path = folder / kind / f"{key}.json"
+        record = {
+            "키": key,
+            "종류": kind,
+            "문서": json.loads(path.read_bytes()),
+            "자리": places.pop(key, None),
+            "남김": keep,
+            "옮긴곳": moved[key],
+            "때": when,
+            "누가": session.get("name"),
+        }
+        atomic_write_json(folder / GONE / f"{key}.json", record)
+        path.unlink()
+        done.append({"키": key, "옮긴곳수": len(moved[key])})
+    if done:
+        atomic_write_json(folder / pre_folders.file_of(kind), {**tree_doc, "자리": places})
+    return {"합침": done, "남김": kept, **find(folder, kind)}
+
+
+def undo(session: Session, folder: Path, kind: str, key: str) -> dict[str, Any]:
+    """`_합친것/<키>` 되돌림 — 문서 · 나무 자리 · 옮긴 참조(아직 남김을 가리키고 쓸 수 있는 곳)."""
+    mine = refs.where(folder)
+    rec_path = folder / GONE / f"{key}.json"
+    try:
+        rec = json.loads(rec_path.read_bytes())
+    except (OSError, ValueError):
+        raise _bad(404, f"합친 것에 없음 「{key}」") from None
+    if rec.get("종류") != kind:
+        raise _bad(404, f"합친 것에 없음 「{key}」")
+    path = folder / kind / f"{key}.json"
+    if path.exists():
+        raise _bad(409, f"「{key}」 키를 그새 다른 문서가 씀 — 되돌릴 수 없음")
+    atomic_write_json(path, rec["문서"])
+    with store.at(folder):
+        tree_doc, _ = pre_folders._read(kind)
+    if rec.get("자리"):
+        places = {**(tree_doc.get("자리") or {}), key: rec["자리"]}
+        atomic_write_json(folder / pre_folders.file_of(kind), {**tree_doc, "자리": places})
+    keep, back, miss = rec.get("남김") or {}, 0, []
+    new = _ref(mine, key)
+    # ponytail: 옮긴 뒤 그 쓰는 곳이 남김을 다른 줄에서 따로 담았으면 그 줄까지 되돌림 — 드문 꼴
+    for one in rec.get("옮긴곳") or []:
+        at = (one.get("층"), one.get("주인"))
+        user = refs.folder_of(*at) / str(one.get("종류")) / f"{one.get('이름')}.json"
+        try:
+            if not _can_write(session, at) or not user.is_file():
+                raise store.StoreError(403, "권한 밖 · 없음")
+            _rewrite(user, str(one.get("종류")), {refs.ref_id(keep)}, new)
+            back += 1
+        except store.StoreError as error:
+            miss.append(f"{one.get('종류')} {one.get('이름')} — {error.detail}")
+    rec_path.unlink()
+    return {"되돌림": key, "되돌린곳수": back, "못한곳": miss, **find(folder, kind)}
+
+
+def _run(fn, *args):
+    try:
+        return fn(*args)
+    except store.StoreError as e:
+        raise HTTPException(status_code=e.status, detail=e.detail) from e
+
+
+@router.get("/layers/{layer}/{kind}-same")
+def library_same(
+    layer: Layer, kind: Kind, owner: str | None = None, session: Session = Depends(verify_session)
+) -> dict:
+    """[중복 찾기] — 이 층 + 위 층 같은 내용 묶음 · 합친 것 목록(읽기 = 그 층 쓰기 권한)."""
+    return _run(find, _root(session, layer, owner, write=True), kind)
+
+
+@router.post("/layers/{layer}/{kind}-same/merge")
+def library_same_merge(
+    layer: Layer,
+    kind: Kind,
+    body: MergeBody,
+    owner: str | None = None,
+    session: Session = Depends(verify_session),
+) -> dict:
+    """합치기 — 쓰는 곳 참조 → 남김 · 지운 문서 `_합친것/` · 판 · 지문 다르면 409."""
+    return _run(merge, session, _root(session, layer, owner, write=True), kind, body)
+
+
+@router.post("/layers/{layer}/{kind}-same/undo")
+def library_same_undo(
+    layer: Layer,
+    kind: Kind,
+    body: UndoBody,
+    owner: str | None = None,
+    session: Session = Depends(verify_session),
+) -> dict:
+    """되돌림 — `_합친것/<키>` 문서 · 나무 자리 · 옮긴 참조."""
+    return _run(undo, session, _root(session, layer, owner, write=True), kind, body.키)
diff --git a/M02_MasterTemplete/M02_MasterTemplete_Library_Same.css b/M02_MasterTemplete/M02_MasterTemplete_Library_Same.css
new file mode 100644
index 000000000..1250994b8
--- /dev/null
+++ b/M02_MasterTemplete/M02_MasterTemplete_Library_Same.css
@@ -0,0 +1,30 @@
+/* M02 서고 [중복 찾기](733-3) — 자리만 · 단추 · 표 · 배지 꼴은 부품 상자 */
+.m02-same {
+  display: flex;
+  flex-direction: column;
+  gap: 16px;
+}
+.m02-same__note:empty {
+  display: none;
+}
+.m02-same__group {
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+}
+.m02-same__head {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+}
+.m02-same__head > span {
+  flex: 1;
+  min-width: 0;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+.m02-same__group h4 {
+  margin: 0;
+  font-size: var(--text-body);
+}
diff --git a/M02_MasterTemplete/M02_MasterTemplete_Library_Same.ts b/M02_MasterTemplete/M02_MasterTemplete_Library_Same.ts
new file mode 100644
index 000000000..29e286a67
--- /dev/null
+++ b/M02_MasterTemplete/M02_MasterTemplete_Library_Same.ts
@@ -0,0 +1,308 @@
+/* =============================================================================
+ * M02_MasterTemplete_Library_Same.ts
+ * 서고 [중복 찾기](733-3 · 요구서_572 3장 4) — 좌측 일위대가 · 단가산출 나무 메뉴에서 엶.
+ * 창 = 같은 내용 묶음(이 층 + 위 층 · 서버 `GET {kind}-same`) · 묶음마다 꼬리표(내용 같음 · 수량만 다름) ·
+ * 문서 줄(층 · 키 · 이름 · 구분 · 쓰는 곳 수) · [남김] 고르기 · [합치기](물음 → 서버 `merge` · 이 층 나머지 문서를
+ * 지움 · 쓰는 곳 참조를 남김으로) · 결과(합침 · 권한 밖 남김) · 합친 것 목록 [되돌림](`undo`).
+ * 권한 = 그 층 쓰기(서버가 봄) · 판 다르면 409 → 다시 찾음.
+ * ========================================================================== */
+
+import { createBadge } from "@ui/ui_template_badge";
+import { createButton, el, showToast } from "@ui/ui_template_elements";
+import { createEmpty } from "@ui/ui_template_empty";
+import { currentLanguageIndex } from "@ui/ui_template_locale";
+import { askConfirm, openModal } from "@ui/ui_template_modal";
+import { createTable, type Cell } from "@ui/ui_template_table";
+import { createText } from "@ui/ui_template_text";
+import { call, StaleError, type Layer, type LibraryKind } from "./M02_MasterTemplete_Api_Fetch";
+import "./M02_MasterTemplete_Library_Same.css";
+
+const TEXT = {
+  Title: ["중복 찾기", "Find duplicates"],
+  Close: ["닫기", "Close"],
+  Intro: [
+    "내용이 같은 문서 묶음 — [남김]을 고르고 [합치기]하면 이 층의 나머지 문서를 지우고 쓰는 곳을 남김으로 옮김 · [되돌림]으로 되살림",
+    "Groups with the same content — pick [Keep] and [Merge]: other docs on this layer are removed and their users point to the kept one · [Undo] restores",
+  ],
+  None: ["같은 내용 문서 없음", "No duplicates"],
+  Loading: ["찾는 중…", "Searching…"],
+  Same: ["내용 같음", "Same content"],
+  QtyOnly: ["수량만 다름", "Quantity differs"],
+  Layer: ["층", "Layer"],
+  Key: ["키", "Key"],
+  Name: ["이름", "Name"],
+  Class: ["구분", "Category"],
+  Used: ["쓰는 곳", "Used by"],
+  Keep: ["남김", "Keep"],
+  Kept: ["남김 ✓", "Kept ✓"],
+  Merge: ["합치기", "Merge"],
+  Upper: ["위 층", "Upper"],
+  system: ["마스터", "Master"],
+  company: ["회사", "Company"],
+  personal: ["개인", "Personal"],
+  project: ["프로젝트", "Project"],
+  Ask: [
+    "「{keep}」 하나로 합침 — 이 층 문서 {n} 개를 지우고 쓰는 곳 참조를 옮김 · 지운 문서는 [되돌림]으로 되살림",
+    "Merge into “{keep}” — remove {n} doc(s) on this layer and move their users · [Undo] restores",
+  ],
+  AskQty: [
+    "⚠ 실무 수량(엑셀 규격)이 서로 다름 — 지운 문서의 실무 수량 기록은 되돌림 때까지 안 보임",
+    "⚠ Practice quantities differ — removed docs' quantity record is hidden until undo",
+  ],
+  Done: ["합침 {n} · 옮긴 쓰는 곳 {m}", "Merged {n} · moved users {m}"],
+  Left: [
+    "남김 — 「{key}」 쓰는 곳 {n}(권한 밖 · 못 옮김): {list}",
+    "Kept “{key}” — {n} user(s) not moved: {list}",
+  ],
+  Gone: ["합친 것(되돌림)", "Merged (undo)"],
+  GoneNone: ["합친 것 없음", "Nothing merged"],
+  When: ["때", "When"],
+  Into: ["남김", "Kept as"],
+  Undo: ["되돌림", "Undo"],
+  AskUndo: [
+    "「{key}」 되돌림 — 문서를 되살리고 옮긴 쓰는 곳 {n} 을 다시 이 문서로",
+    "Undo “{key}” — restore it and point its {n} user(s) back",
+  ],
+  Undone: ["되돌림 — 쓰는 곳 {n}", "Undone — users {n}"],
+  Stale: ["그새 바뀜 — 다시 찾음", "Changed meanwhile — searching again"],
+} as const;
+type TextKey = keyof typeof TEXT;
+const tx = (key: TextKey, vars: Record<string, string | number> = {}): string =>
+  Object.entries(vars).reduce(
+    (s, [k, v]) => s.replace(`{${k}}`, String(v)),
+    String(TEXT[key][currentLanguageIndex as 0 | 1] ?? TEXT[key][0]),
+  );
+
+/** 나무 메뉴 글 */
+export const sameLabel = (): string => tx("Title");
+
+export interface SameRef {
+  층: Layer;
+  주인: string | null;
+  키: string;
+}
+export interface SameDoc extends SameRef {
+  이름: string;
+  구분: string;
+  상세구분: string;
+  쓰는곳수: number;
+  위층: boolean;
+}
+export interface SameGroup {
+  지문: string;
+  꼬리표: "내용 같음" | "수량만 다름";
+  문서: SameDoc[];
+}
+export interface GoneRow {
+  키: string;
+  이름: string;
+  남김: SameRef;
+  때: string;
+  옮긴곳수: number;
+}
+export interface SameView {
+  판: string;
+  묶음: SameGroup[];
+  합친것: GoneRow[];
+}
+export interface MergeResult extends SameView {
+  합침: { 키: string; 옮긴곳수: number }[];
+  남김: { 키: string; 쓰는곳: string[] }[];
+}
+
+const path = (kind: LibraryKind, layer: Layer, owner: string | null, tail = ""): string =>
+  `/layers/${layer}/${kind}-same${tail}${owner && layer !== "system" ? `?owner=${encodeURIComponent(owner)}` : ""}`;
+const post = <T>(url: string, body: unknown): Promise<T> =>
+  call<T>(url, { method: "POST", body: JSON.stringify(body) });
+const why = (error: unknown): string => (error instanceof Error ? error.message : "");
+
+/** 묶음 하나에서 남김을 고를 때 지울 것 — 이 층(위 층 아님) 문서 가운데 남김 아닌 것 */
+export const goneOf = (group: SameGroup, keep: SameRef): string[] =>
+  group.문서
+    .filter((d) => !d.위층 && !(d.층 === keep.층 && d.주인 === keep.주인 && d.키 === keep.키))
+    .map((d) => d.키);
+
+export interface SameOptions {
+  kind: LibraryKind;
+  layer: Layer;
+  owner: string | null;
+  /** 합치기 · 되돌림 뒤 — 좌측 나무 다시 그림 */
+  changed: () => void;
+}
+
+export function openLibrarySame(opt: SameOptions): void {
+  const host = el("div", { className: "m02-same", attrs: { "data-library-same": opt.kind } });
+  const note = el("div", { className: "m02-same__note" });
+  let view: SameView | null = null;
+
+  const load = async (): Promise<void> => {
+    host.replaceChildren(createEmpty({ text: tx("Loading"), small: true }));
+    try {
+      view = await call<SameView>(path(opt.kind, opt.layer, opt.owner));
+    } catch (error) {
+      host.replaceChildren(createText(why(error), "error"));
+      return;
+    }
+    draw();
+  };
+
+  const run = async (job: () => Promise<SameView>, done: (got: SameView) => void) => {
+    try {
+      const got = await job();
+      view = got;
+      done(got);
+      opt.changed();
+      draw();
+    } catch (error) {
+      showToast(
+        error instanceof StaleError ? `${tx("Stale")} — ${why(error)}` : why(error),
+        "error",
+      );
+      if (error instanceof StaleError) void load();
+    }
+  };
+
+  const merge = async (group: SameGroup, keep: SameDoc): Promise<void> => {
+    const gone = goneOf(group, keep);
+    const message = [
+      tx("Ask", { keep: `${keep.키} ${keep.이름}`, n: gone.length }),
+      ...(group.꼬리표 === "수량만 다름" ? [tx("AskQty")] : []),
+    ].join("\n");
+    if (!view || !gone.length) return;
+    if (!(await askConfirm({ message, okLabel: tx("Merge"), title: tx("Title") }))) return;
+    const 판 = view.판;
+    await run(
+      () =>
+        post<MergeResult>(path(opt.kind, opt.layer, opt.owner, "/merge"), {
+          남김: { 층: keep.층, 주인: keep.주인, 키: keep.키 },
+          지움: gone,
+          판,
+        }),
+      (got) => {
+        const res = got as MergeResult;
+        const moved = res.합침.reduce((n, r) => n + r.옮긴곳수, 0);
+        showToast(tx("Done", { n: res.합침.length, m: moved }), "success");
+        note.replaceChildren(
+          ...res.남김.map((k) =>
+            createText(
+              tx("Left", { key: k.키, n: k.쓰는곳.length, list: k.쓰는곳.join(" · ") }),
+              "warning",
+            ),
+          ),
+        );
+      },
+    );
+  };
+
+  const undo = async (row: GoneRow): Promise<void> => {
+    const message = tx("AskUndo", { key: `${row.키} ${row.이름}`, n: row.옮긴곳수 });
+    if (!(await askConfirm({ message, okLabel: tx("Undo"), title: tx("Title") }))) return;
+    await run(
+      () => post<SameView>(path(opt.kind, opt.layer, opt.owner, "/undo"), { 키: row.키 }),
+      (got) => {
+        const back = (got as SameView & { 되돌린곳수?: number }).되돌린곳수 ?? 0;
+        showToast(tx("Undone", { n: back }), "success");
+        note.replaceChildren();
+      },
+    );
+  };
+
+  const groupBlock = (group: SameGroup): HTMLElement => {
+    let keep = group.문서[0];
+    const columns = [
+      { label: tx("Keep"), width: "88px" },
+      { label: tx("Layer"), width: "88px" },
+      { label: tx("Key"), width: "112px" },
+      { label: tx("Name") },
+      { label: tx("Class") },
+      { label: tx("Used"), width: "72px", align: "end" as const },
+    ];
+    const tableHost = el("div");
+    const paint = (): void => {
+      const rows: Cell[][] = group.문서.map((d) => [
+        createButton({
+          label: d === keep ? tx("Kept") : tx("Keep"),
+          variant: d === keep ? "filled" : "ghost",
+          size: "sm",
+          onClick: () => {
+            keep = d;
+            paint();
+          },
+        }),
+        d.위층 ? `${tx(d.층)} · ${tx("Upper")}` : tx(d.층),
+        d.키,
+        d.이름,
+        [d.구분, d.상세구분].filter(Boolean).join(" / "),
+        String(d.쓰는곳수),
+      ]);
+      tableHost.replaceChildren(createTable(columns, rows, { density: "data" }));
+      mergeButton.disabled = !goneOf(group, keep).length;
+    };
+    const mergeButton = createButton({
+      label: tx("Merge"),
+      size: "sm",
+      onClick: () => void merge(group, keep),
+    });
+    const tag = group.꼬리표 === "수량만 다름" ? tx("QtyOnly") : tx("Same");
+    const head = el("div", {
+      className: "m02-same__head",
+      children: [
+        createBadge(tag, group.꼬리표 === "수량만 다름" ? "warning" : "info"),
+        el("span", { text: `${group.문서[0].이름} · ${group.문서.length}` }),
+        mergeButton,
+      ],
+    });
+    paint();
+    return el("section", {
+      className: "m02-same__group",
+      attrs: { "data-same-group": group.지문 },
+      children: [head, tableHost],
+    });
+  };
+
+  const goneBlock = (rows: GoneRow[]): HTMLElement => {
+    const columns = [
+      { label: tx("Key"), width: "112px" },
+      { label: tx("Name") },
+      { label: tx("Into"), width: "140px" },
+      { label: tx("When"), width: "160px" },
+      { label: "", width: "88px" },
+    ];
+    const cells: Cell[][] = rows.map((r) => [
+      r.키,
+      r.이름,
+      `${tx(r.남김.층)} ${r.남김.키}`,
+      r.때.replace("T", " "),
+      createButton({
+        label: tx("Undo"),
+        variant: "ghost",
+        size: "sm",
+        onClick: () => void undo(r),
+      }),
+    ]);
+    return el("section", {
+      className: "m02-same__group",
+      attrs: { "data-same-gone": "" },
+      children: [
+        el("h4", { text: tx("Gone") }),
+        createTable(columns, cells, { density: "data", empty: tx("GoneNone") }),
+      ],
+    });
+  };
+
+  const draw = (): void => {
+    if (!view) return;
+    const groups = view.묶음.length
+      ? view.묶음.map(groupBlock)
+      : [createEmpty({ text: tx("None"), small: true })];
+    host.replaceChildren(createText(tx("Intro"), "muted"), note, ...groups, goneBlock(view.합친것));
+  };
+
+  openModal({
+    title: tx("Title"),
+    closeLabel: tx("Close"),
+    width: "960px",
+    mount: (body) => body.append(host),
+  });
+  void load();
+}
diff --git a/M02_MasterTemplete/M02_MasterTemplete_UI_Side_Library.ts b/M02_MasterTemplete/M02_MasterTemplete_UI_Side_Library.ts
index 7bb16a460..c355ce634 100644
--- a/M02_MasterTemplete/M02_MasterTemplete_UI_Side_Library.ts
+++ b/M02_MasterTemplete/M02_MasterTemplete_UI_Side_Library.ts
@@ -37,6 +37,7 @@ import {
   type PrecomboTree,
 } from "./M02_MasterTemplete_Api_Fetch";
 import { nameDialog } from "./M02_MasterTemplete_Library_List";
+import { openLibrarySame, sameLabel } from "./M02_MasterTemplete_Library_Same";
 import type { Root } from "./M02_MasterTemplete_Layer";
 import { tc } from "./M02_MasterTemplete_Labor_Text";
 import { askText } from "./M02_MasterTemplete_TreePanel_Dialogs";
@@ -307,8 +308,14 @@ export function buildLibrarySection(opt: LibraryOptions): LibraryHandle {
       ...(got
         ? [item(L("M02_TreePaste").replace("{n}", String(got.refs.length)), () => void paste(path))]
         : []),
+      ...(path.length ? [] : [item(sameLabel(), () => same())]),
     ];
   };
+  /** [중복 찾기](733-3) — 그 층 같은 내용 묶음 · 합치기 · 되돌림 */
+  const same = (): void => {
+    const at = opt.scope();
+    openLibrarySame({ kind, layer: at.layer, owner: at.owner, changed: () => void refresh() });
+  };
   /** 오른쪽 클릭 — 고른 것 안의 줄이면 고른 것 전부(복사 · 지우기) · 아니면 그 줄 하나 */
   const menuFor = (id: string, single: () => TreeMenuItem[]): TreeMenuItem[] => {
     if (!picked.has(id)) setPicked(new Set([id]), id);