diff --git a/payphone/cogs/admin/cog.py b/payphone/cogs/admin/cog.py
index 3a1ea05..c8d5459 100644
--- a/payphone/cogs/admin/cog.py
+++ b/payphone/cogs/admin/cog.py
@@ -22,7 +22,7 @@ class Admin(base.Cog):
     def cog_unload(self) -> None:
         self.update_leaderboard.cancel()
 
-    @tasks.loop(minutes=15)
+    @tasks.loop(seconds=30)
     async def update_leaderboard(self) -> None:
         """Updates the leaderboard."""
 
diff --git a/payphone/core/utils.py b/payphone/core/utils.py
index d361918..04cdae0 100644
--- a/payphone/core/utils.py
+++ b/payphone/core/utils.py
@@ -22,7 +22,9 @@ def deduplicate(i: Iterable[T], key: Callable[[T], U] = lambda i: i) -> list[T]:
     result = []
 
     for item in i:
-        if key(item) not in found_keys:
+        k = key(item)
+        if k not in found_keys:
             result.append(item)
+            found_keys.add(k)
 
     return result