diff --git a/src/app/api/workouts/batch/route.ts b/src/app/api/workouts/batch/route.ts
index 9b127601b..d1b5a758a 100644
--- a/src/app/api/workouts/batch/route.ts
+++ b/src/app/api/workouts/batch/route.ts
@@ -477,16 +477,21 @@ async function postBatch(request: NextRequest): Promise<Response> {
       workoutId: string;
       samples: NonNullable<Prepared["samples"]>;
     }> = [];
+    /** Workouts already claimed by an earlier entry of THIS batch. */
+    const enrichClaimed = new Set<string>();
     for (const p of survivors) {
       const keyTuple = p.dedupKey
         ? `${p.dedupKey.source}::${p.dedupKey.externalId}`
         : null;
       const known = keyTuple !== null ? existingByKey.get(keyTuple) : undefined;
       if (known) {
-        if (p.samples && !known.hasSeries) {
+        if (p.samples && !known.hasSeries && !enrichClaimed.has(known.id)) {
+          enrichClaimed.add(known.id);
           // Enrichment. The status is assigned after the write, because
           // a concurrent writer may get the series in first — in which
-          // case this entry is the plain duplicate it always was.
+          // case this entry is the plain duplicate it always was. A
+          // second entry of this batch naming the same workout takes the
+          // duplicate arm above: one workout, one series, one `enriched`.
           toEnrich.push({
             index: p.index,
             workoutId: known.id,
diff --git a/tests/integration/workout-batch-enrich.test.ts b/tests/integration/workout-batch-enrich.test.ts
index ff9d98125..b63bb4b0e 100644
--- a/tests/integration/workout-batch-enrich.test.ts
+++ b/tests/integration/workout-batch-enrich.test.ts
@@ -213,6 +213,33 @@ describe("POST /api/workouts/batch — HR series enrichment (real Postgres)", ()
     ).toBe(1);
   });
 
+  it("reports one enrichment when two entries in one batch aim at the same workout", async () => {
+    await post({ workouts: [baseWorkout("hk-uuid-enrich-007")] });
+
+    // Same external id twice, far enough apart in time that the
+    // write-time twin dedup keeps both entries. Only one series can land.
+    const res = await post({
+      workouts: [
+        baseWorkout("hk-uuid-enrich-007", { samples: SERIES }),
+        baseWorkout("hk-uuid-enrich-007", {
+          startedAt: "2026-05-14T09:00:00.000Z",
+          endedAt: "2026-05-14T09:45:00.000Z",
+          samples: [{ t: "2026-05-14T09:00:00.000Z", hr: 155 }],
+        }),
+      ],
+    });
+
+    expect(res.status).toBe(200);
+    expect(
+      res.data.entries.filter((e) => e.status === "enriched"),
+    ).toHaveLength(1);
+    expect(
+      await getPrismaClient().workoutSamples.count({
+        where: { workout: { userId: TEST_USER_ID } },
+      }),
+    ).toBe(1);
+  });
+
   it("leaves every workout column byte-identical across an enrichment", async () => {
     await post({
       workouts: [