diff --git a/app/services/batch_store.ts b/app/services/batch_store.ts
index 11a5b6b..6d40d33 100644
--- a/app/services/batch_store.ts
+++ b/app/services/batch_store.ts
@@ -185,22 +185,36 @@ class BatchStore {
         // The first upload of a key keeps the key; later ones are key:2, key:3, …
         const { rows: counts } = await trx.rawQuery(`SELECT identity_key, count(*) AS n FROM releases WHERE identity_key = ANY(?) GROUP BY 1`, [[...new Set(fresh.map((r) => r.key))]])
         const taken = new Map<string, number>(counts.map((c: { identity_key: string; n: string }) => [c.identity_key, Number(c.n)]))
-        const inserts = fresh.map((r) => {
+        const numbered = (r: ReleaseChunk) => {
           const n = (taken.get(r.key) ?? 0) + 1
           taken.set(r.key, n)
           return { release_key: n === 1 ? r.key : `${r.key}:${n}`, key: r.key, upload: r.upload, ...row(r) }
-        })
-        const { rows } = await trx.rawQuery(
-          `INSERT INTO releases (release_key, identity_key, group_id, name, source, poster, groups, posted_at, last_posted_at, file_total, files, segments, bytes, chunks, first_article, last_article, readable, has_par2, complete)
-           SELECT v.release_key, v.key, ?, v.name, v.source, v.poster, v.groups, to_timestamp(v.first / 1000.0), to_timestamp(v.last / 1000.0), v.file_total, v.files, v.segments, v.bytes, 1,
-                  v.first_article, v.last_article, v.readable, v.has_par2, CASE WHEN v.file_total IS NULL THEN NULL ELSE v.files >= v.file_total END
-           FROM jsonb_to_recordset(?::jsonb) AS v(release_key text, key text, name text, source text, poster text, groups jsonb, first bigint, last bigint, file_total int, files int, segments bigint, bytes bigint, first_article bigint, last_article bigint, readable boolean, has_par2 boolean)
-           RETURNING id, release_key`,
-          [groupId, JSON.stringify(inserts)]
-        )
-        const byReleaseKey = new Map<string, number>(rows.map((x: { id: string; release_key: string }) => [x.release_key, Number(x.id)]))
-        for (const r of inserts) ids.set(slot(r.key, r.upload), byReleaseKey.get(r.release_key)!)
-        out.newReleases += rows.length
+        }
+        let inserts = fresh.map(numbered)
+        // Writers of other groups number the same key at the same time (a spam post crossposted to 67
+        // groups; only the group is locked): a number taken meanwhile is skipped, and the next one tried.
+        for (let attempt = 0; inserts.length > 0; attempt++) {
+          if (attempt === 20) throw new Error(`No free release key for ${inserts[0].key}`)
+          const { rows } = await trx.rawQuery(
+            `INSERT INTO releases (release_key, identity_key, group_id, name, source, poster, groups, posted_at, last_posted_at, file_total, files, segments, bytes, chunks, first_article, last_article, readable, has_par2, complete)
+             SELECT v.release_key, v.key, ?, v.name, v.source, v.poster, v.groups, to_timestamp(v.first / 1000.0), to_timestamp(v.last / 1000.0), v.file_total, v.files, v.segments, v.bytes, 1,
+                    v.first_article, v.last_article, v.readable, v.has_par2, CASE WHEN v.file_total IS NULL THEN NULL ELSE v.files >= v.file_total END
+             FROM jsonb_to_recordset(?::jsonb) AS v(release_key text, key text, name text, source text, poster text, groups jsonb, first bigint, last bigint, file_total int, files int, segments bigint, bytes bigint, first_article bigint, last_article bigint, readable boolean, has_par2 boolean)
+             ON CONFLICT (release_key) DO NOTHING
+             RETURNING id, release_key`,
+            [groupId, JSON.stringify(inserts)]
+          )
+          const byReleaseKey = new Map<string, number>(rows.map((x: { id: string; release_key: string }) => [x.release_key, Number(x.id)]))
+          const missed: typeof inserts = []
+          for (const r of inserts) {
+            const id = byReleaseKey.get(r.release_key)
+            if (id === undefined) missed.push(r)
+            else ids.set(slot(r.key, r.upload), id)
+          }
+          out.newReleases += rows.length
+          const chunks = new Map(fresh.map((r) => [slot(r.key, r.upload), r]))
+          inserts = missed.map((r) => numbered(chunks.get(slot(r.key, r.upload))!))
+        }
       }
     }
 
diff --git a/tests/functional/batch_store.spec.ts b/tests/functional/batch_store.spec.ts
index c36abed..4bfba0c 100644
--- a/tests/functional/batch_store.spec.ts
+++ b/tests/functional/batch_store.spec.ts
@@ -127,4 +127,15 @@ test.group('BatchStore', (group) => {
     assert.lengthOf(rows, 2)
     assert.equal(rows[0].identity_key, rows[1].identity_key)
   })
+
+  test('a release key taken meanwhile by another group\'s writer is skipped for the next number', async ({ assert }) => {
+    await storeIn(GROUP, 1, upload(10, 'Some.Show.S01E01.1080p.mkv', 2, 'Some.Show.S01E01.1080p [1/1]', '2026-10-05T10:00:00Z'))
+    const [first] = await releasesOf()
+    // As if another group's batch numbered the key at the same moment: key:2 exists, not counted for this key.
+    const [g] = await db.table('groups').insert({ name: 'alt.binaries.third', priority: 3 }).returning('id')
+    await db.table('releases').insert({ release_key: `${first.identity_key}:2`, identity_key: 'someone-else', group_id: g.id, name: 'x', source: 'subject', poster: 'p', groups: JSON.stringify([]), files: 0, segments: 0, bytes: 0, chunks: 0 })
+    await storeIn('alt.binaries.other', 1, upload(10, 'Some.Show.S01E01.1080p.mkv', 2, 'Some.Show.S01E01.1080p [1/1]', '2026-10-05T10:01:00Z', 'alt.binaries.other'))
+    const keys = (await releasesOf()).filter((r) => r.identity_key === first.identity_key).map((r) => r.release_key)
+    assert.deepEqual(keys, [first.identity_key, `${first.identity_key}:3`])
+  })
 })