diff --git a/sharded_queue/__init__.py b/sharded_queue/__init__.py
index e90ccf2..804d85c 100644
--- a/sharded_queue/__init__.py
+++ b/sharded_queue/__init__.py
@@ -310,7 +310,7 @@ async def handle(self, *requests: DeferredRequest) -> None:
         ]
 
         for pipe in set([pipe for (pipe, _) in todo]):
-            ready = [
+            ready: list[str] = [
                 msg for msg in
                 [
                     self.worker.queue.serializer.serialize(request)
@@ -320,6 +320,7 @@ async def handle(self, *requests: DeferredRequest) -> None:
                 if not await self.worker.queue.storage.contains(pipe, msg)
             ]
 
+            ready = list(set(ready))
             if len(ready):
                 await self.worker.queue.storage.append(pipe, *ready)
 
diff --git a/tests/test_deferred.py b/tests/test_deferred.py
index 5fd4ec3..1a9d778 100644
--- a/tests/test_deferred.py
+++ b/tests/test_deferred.py
@@ -36,13 +36,22 @@ async def test_deferred() -> None:
     assert await queue.storage.length(drop_pipe) == 0
     assert await queue.storage.length(deferred_pipe) == 1
 
-    await worker.loop(1)
+    await queue.register(
+        DropBucket,
+        BucketRequest(1),
+        defer=timedelta(milliseconds=5),
+    )
+
     assert await queue.storage.length(drop_pipe) == 0
-    assert await queue.storage.length(deferred_pipe) == 1
+    assert await queue.storage.length(deferred_pipe) == 2
+
+    await worker.loop(2)
+    assert await queue.storage.length(drop_pipe) == 0
+    assert await queue.storage.length(deferred_pipe) == 2
 
     await sleep(0.01)
 
-    await worker.loop(1)
+    await worker.loop(2)
     assert await queue.storage.length(drop_pipe) == 1
     assert await queue.storage.length(deferred_pipe) == 0