diff --git a/resources/tester/test_est_progress_workflow.py b/resources/tester/test_est_progress_workflow.py
index 6b88b1989..565b9a03e 100644
--- a/resources/tester/test_est_progress_workflow.py
+++ b/resources/tester/test_est_progress_workflow.py
@@ -1,6 +1,23 @@
 from test_est_rea_parity import run
 
 
+def test_progress_rejects_ambiguous_inputs_without_applying_them_to_multiple_rows():
+    result = run(
+        "math",
+        """(()=>{
+      const p=EstNative.empty();p.options.SourceRefresh=false;
+      p.tables.EstMainDat=[{Code:'A',GN:10,GU:100},{Code:'A',GN:20,GU:100},
+        {PkID:3,Code:'B',GN:10,GU:100},{LinkIndex:54}];
+      p.progress=[{id:'one',inputs:{A:{Gum:2},'3':{Gum:3}}}];
+      const out=EstProgress.calculate(EstNative.calculate(p),'one');let rejected=false;
+      try{EstProgress.lock(EstNative.calculate(p),'one')}catch{rejected=true}
+      return {out,rejected};
+    })()""",
+    )
+    assert result["rejected"] and result["out"]["errors"]
+    assert [row["GumTC"] for row in result["out"]["rows"][:3]] == [0, 0, 300]
+
+
 def test_progress_amount_input_preserves_exact_money_and_component_total():
     result = run(
         "math",
diff --git a/tools/est-test/native-actions.js b/tools/est-test/native-actions.js
index 0943f3bed..dc6eed120 100644
--- a/tools/est-test/native-actions.js
+++ b/tools/est-test/native-actions.js
@@ -552,6 +552,8 @@ const EstActions = (() => {
         if (node.matches("[data-progress]")) {
           const round = project.progress.find((r) => r.id === state.roundId);
           if (round.locked) throw Error("확정 회차입니다.");
+          if (EstProgress.ambiguousKeys(project.tables.EstMainDat).has(node.dataset.key))
+            throw Error("기성 내역 식별자가 중복되어 입력할 수 없습니다.");
           const value = node.type === "number" ? Number(node.value) : node.value;
           if (node.type === "number" && !Number.isFinite(value)) throw Error("수치 입력 오류");
           EstApp.change(() => {
diff --git a/tools/est-test/native-business-actions.js b/tools/est-test/native-business-actions.js
index 69eb997f7..3f9fe3281 100644
--- a/tools/est-test/native-business-actions.js
+++ b/tools/est-test/native-business-actions.js
@@ -109,9 +109,19 @@ const EstBusinessActions = (() => {
           },
           { name: "ratio", label: "비율 %", type: "number", value: 100 },
         ],
-        (values) =>
+        (values) => {
+          const value = numeric(values.ratio);
+          const ambiguous = EstProgress.ambiguousKeys(project.tables.EstMainDat);
+          const hasAmbiguous = project.tables.EstMainDat.some(
+            (row, index) =>
+              Number(row.Level || 0) <= 0 &&
+              Number(row.CalcIndex || 0) < 2 &&
+              ![54, 55, 58, 59, 62, 67].includes(Number(row.LinkIndex)) &&
+              !(values.mode === "full" && Number(row.LinkIndex) === 57) &&
+              ambiguous.has(EstBusiness.rowKey(row, index)),
+          );
+          if (hasAmbiguous) throw Error("기성 내역 식별자가 중복되어 일괄 입력할 수 없습니다.");
           EstApp.change(() => {
-            const value = numeric(values.ratio);
             project.tables.EstMainDat.forEach((row, index) => {
               if (
                 Number(row.Level) > 0 ||
@@ -127,7 +137,8 @@ const EstBusinessActions = (() => {
               round.inputs[key][values.prefix] =
                 values.mode === "full" ? Number(row.GN) || 0 : value;
             });
-          }, false),
+          }, false);
+        },
       );
     } else if (name === "load-progress-exclusion") {
       const locked = project.progress.filter((round) => round.locked && round.result);
diff --git a/tools/est-test/native-progress.js b/tools/est-test/native-progress.js
index c71f624f7..b149e162f 100644
--- a/tools/est-test/native-progress.js
+++ b/tools/est-test/native-progress.js
@@ -8,6 +8,14 @@ const EstProgress = (() => {
     return Math.max(0, (mantissa.split(".")[1]?.length || 0) - Number(exponent || 0));
   };
   const ordinary = (row) => num(row.Level) === 0 && ![54, 55, 58, 59].includes(num(row.LinkIndex));
+  function ambiguousKeys(rows) {
+    const counts = new Map();
+    rows.forEach((row, index) => {
+      const key = EstBusiness.rowKey(row, index);
+      counts.set(key, (counts.get(key) || 0) + 1);
+    });
+    return new Set([...counts].filter(([, count]) => count > 1).map(([key]) => key));
+  }
   function distribute(amount, row, digits) {
     const parts = components.map((field) => num(row[field]));
     const base = sum(row);
@@ -31,6 +39,7 @@ const EstProgress = (() => {
     const errors = [],
       position = project.progress.indexOf(round),
       key = EstBusiness.rowKey;
+    const ambiguous = ambiguousKeys(rows);
     const earlier = project.progress.slice(0, position);
     if (earlier.some((item) => !item.locked)) errors.push("전회 기성 회차를 먼저 확정하세요.");
     const previous = earlier.at(-1)?.result,
@@ -39,8 +48,10 @@ const EstProgress = (() => {
     const separated = round.separateComponents !== false;
     rows.forEach((row, index) => {
       const id = key(row, index),
-        input = round.inputs?.[id] || {},
-        old = oldRows.get(id);
+        input = ambiguous.has(id) ? {} : round.inputs?.[id] || {},
+        old = ambiguous.has(id) ? null : oldRows.get(id);
+      if (ambiguous.has(id) && (round.inputs?.[id] || oldRows.has(id)))
+        errors.push(`기성 내역 식별자가 중복됩니다: ${id}`);
       for (const field of ["GN", "TC", "Ratio", ...components])
         row["Jun" + field] = num(old?.["Total" + field]);
       if (num(row.Level) > 0 || [54, 59].includes(num(row.LinkIndex))) {
@@ -301,5 +312,5 @@ const EstProgress = (() => {
       }
     return project;
   }
-  return { calculate, lock, unlock, rebuild };
+  return { calculate, lock, unlock, rebuild, ambiguousKeys };
 })();