diff --git a/slkspec/core.py b/slkspec/core.py
index eedabb0..8bdc74b 100644
--- a/slkspec/core.py
+++ b/slkspec/core.py
@@ -253,7 +253,7 @@ def _cache_files(self) -> None:
                     items.append(self._file_queue.get())
                     self._file_queue.task_done()
                 try:
-                    self._retrieve_items(items)
+                    self._retrieve_items(list(set(items)))
                 except Exception as error:
                     _ = [
                         self._file_queue.get() for _ in range(self._file_queue.qsize())