diff --git a/client/src/components/admin/AdminRound/AdminRoundContent.jsx b/client/src/components/admin/AdminRound/AdminRoundContent.jsx
index e3f67936..72b33531 100644
--- a/client/src/components/admin/AdminRound/AdminRoundContent.jsx
+++ b/client/src/components/admin/AdminRound/AdminRoundContent.jsx
@@ -76,6 +76,23 @@ function setStoredBatchResults(roundId, results) {
   }
 }
 
+/**
+ * Combine results and batchResults to produce a temporary results-like array
+ * that has all batchResults changes applied.  This allows us to display a
+ * warning if a result is being entered which matches a batched result exactly.
+ */
+function combineResultsAndBatchResults(results, batchResults) {
+  const combinedResults = [...results];
+  batchResults.forEach((batchedResult) => {
+    const i = combinedResults.findIndex((res) => res.id === batchedResult.id);
+    combinedResults[i] = {
+      ...combinedResults[i],
+      attempts: batchedResult.attempts,
+    };
+  });
+  return combinedResults;
+}
+
 function AdminRoundContent({ round, competitionId, officialWorldRecords }) {
   const confirm = useConfirm();
   const { enqueueSnackbar, closeSnackbar } = useSnackbar();
@@ -91,6 +108,9 @@ function AdminRoundContent({ round, competitionId, officialWorldRecords }) {
   const [isBatchMode, setIsBatchMode] = useState(
     () => batchResults.length > 0 || getStoreIsBatchMode(),
   );
+  const [combinedResults, setCombinedResults] = useState(() =>
+    combineResultsAndBatchResults(round.results, batchResults),
+  );
   const formContainerRef = useRef(null);
 
   const [enterResults, { loading }] = useMutation(ENTER_RESULTS, {
@@ -184,7 +204,10 @@ function AdminRoundContent({ round, competitionId, officialWorldRecords }) {
 
   useEffect(() => {
     setStoredBatchResults(round.id, batchResults);
-  }, [round.id, batchResults]);
+    setCombinedResults(
+      combineResultsAndBatchResults(round.results, batchResults),
+    );
+  }, [round, batchResults]);
 
   return (
     <>
@@ -193,6 +216,7 @@ function AdminRoundContent({ round, competitionId, officialWorldRecords }) {
           <ResultAttemptsForm
             result={editedResult}
             results={round.results}
+            combinedResults={combinedResults}
             onResultChange={setEditedResult}
             eventId={round.competitionEvent.event.id}
             format={round.format}
diff --git a/client/src/components/admin/ResultAttemptsForm/ResultAttemptsForm.jsx b/client/src/components/admin/ResultAttemptsForm/ResultAttemptsForm.jsx
index 029a3452..7bbcc035 100644
--- a/client/src/components/admin/ResultAttemptsForm/ResultAttemptsForm.jsx
+++ b/client/src/components/admin/ResultAttemptsForm/ResultAttemptsForm.jsx
@@ -25,6 +25,7 @@ import {
 function ResultAttemptsForm({
   result,
   results,
+  combinedResults, // combined results and batchResults array
   onResultChange,
   eventId,
   format,
@@ -91,15 +92,23 @@ function ResultAttemptsForm({
       const attempts = trimTrailingSkipped(attemptResults).map((result) => ({
         result,
       }));
-      onSubmit(attempts);
+      onSubmit(attempts, result.person);
     });
   }
 
   function confirmSubmission() {
+    // We don't want to show a duplicate warning if the user is submitting
+    // already-entered results for the correct competitor.  This is often used
+    // as a quick way to refresh data without refreshing the whole page.
+    const resultsToCheck = combinedResults.filter(
+      (res) => res.id !== result.id,
+    );
+
     const submissionWarning = attemptResultsWarning(
       attemptResults,
       eventId,
       officialWorldRecords,
+      resultsToCheck,
     );
 
     if (submissionWarning) {
diff --git a/client/src/lib/attempt-result.js b/client/src/lib/attempt-result.js
index c3f085bb..d9ecd91d 100644
--- a/client/src/lib/attempt-result.js
+++ b/client/src/lib/attempt-result.js
@@ -399,6 +399,7 @@ export function attemptResultsWarning(
   attemptResults,
   eventId,
   officialWorldRecords = [],
+  results = [],
 ) {
   const skippedGapIndex =
     trimTrailingSkipped(attemptResults).indexOf(SKIPPED_VALUE);
@@ -482,6 +483,22 @@ export function attemptResultsWarning(
         };
       }
     }
+
+    // Check whether this result is a duplicate of existing results in the same round.
+    // Excludes FMC and all-DNF results since ties are common.
+    if (eventId !== "333fm" && completeAttempts.length > 0) {
+      const matches = findAllMatchingResults(attemptResults, results);
+      if (matches.length > 0) {
+        const matchesString = matches
+          .map((match) => `${match.person.name} (${match.person.id})`)
+          .join(", ");
+        return {
+          description: `The result you're trying to submit matches all results for
+            the following competitor${matches.length > 1 ? "s" : ""}: ${matchesString}.
+            Please check that the results are accurate.`,
+        };
+      }
+    }
   }
   return null;
 }
@@ -545,3 +562,24 @@ function checkForDnsFollowedByValidResult(attemptResults) {
       index > dnsIndex && attempt !== SKIPPED_VALUE && attempt !== DNS_VALUE,
   );
 }
+
+/**
+ * Check whether an attempt matches an existing attempt exactly.
+ */
+function findAllMatchingResults(attemptResults, results) {
+  const filteredAttemptResults = trimTrailingSkipped(attemptResults);
+
+  const matches = results.filter((result) => {
+    if (result.attempts.length !== filteredAttemptResults.length) {
+      return false;
+    }
+    for (let i = 0; i < result.attempts.length; i++) {
+      if (result.attempts[i].result !== filteredAttemptResults[i]) {
+        return false;
+      }
+    }
+    return true;
+  });
+
+  return matches;
+}
diff --git a/client/src/lib/tests/attempt-result.test.js b/client/src/lib/tests/attempt-result.test.js
index 0d8297db..b9b20a89 100644
--- a/client/src/lib/tests/attempt-result.test.js
+++ b/client/src/lib/tests/attempt-result.test.js
@@ -536,6 +536,61 @@ describe("attemptResultsWarning", () => {
       attemptResultsWarning(attemptResults, "333fm", worldRecords),
     ).toEqual(null);
   });
+
+  it("complains about exact duplicate results", () => {
+    const attemptResults = [500, 600, 700, 800, 900];
+    const existingResults = [
+      {
+        attempts: [
+          { result: 500 },
+          { result: 600 },
+          { result: 700 },
+          { result: 800 },
+          { result: 900 },
+        ],
+        person: { id: 2, name: "Person 2" },
+      },
+    ];
+    expect(
+      attemptResultsWarning(attemptResults, "333", [], existingResults),
+    ).toMatchObject({
+      description: `The result you're trying to submit matches all results for
+            the following competitor: Person 2 (2).
+            Please check that the results are accurate.`,
+    });
+  });
+
+  it("does not check for duplicates in FMC", () => {
+    const attemptResults = [25, 26];
+    const existingResults = [
+      {
+        attempts: [{ result: 25 }, { result: 26 }],
+        person: { id: 2, name: "Person 2" },
+      },
+    ];
+    expect(
+      attemptResultsWarning(attemptResults, "333fm", [], existingResults),
+    ).toEqual(null);
+  });
+
+  it("does not warn about all-DNF duplicates", () => {
+    const attemptResults = [-1, -1, -1, -1, -1];
+    const existingResults = [
+      {
+        attempts: [
+          { result: -1 },
+          { result: -1 },
+          { result: -1 },
+          { result: -1 },
+          { result: -1 },
+        ],
+        person: { id: 2, name: "Person 2" },
+      },
+    ];
+    expect(
+      attemptResultsWarning(attemptResults, "333", [], existingResults),
+    ).toEqual(null);
+  });
 });
 
 describe("applyTimeLimit", () => {