diff --git a/telethon/client/telegrambaseclient.py b/telethon/client/telegrambaseclient.py
index cb3ddcab..2a5a41fa 100644
--- a/telethon/client/telegrambaseclient.py
+++ b/telethon/client/telegrambaseclient.py
@@ -196,6 +196,7 @@ class TelegramBaseClient(abc.ABC):
         # Some further state for subclasses
         self._event_builders = []
         self._events_pending_resolve = []
+        self._event_resolve_lock = asyncio.Lock()
 
         # Default parse mode
         self._parse_mode = markdown
diff --git a/telethon/client/updates.py b/telethon/client/updates.py
index d2e5dbde..72d63928 100644
--- a/telethon/client/updates.py
+++ b/telethon/client/updates.py
@@ -159,9 +159,14 @@ class UpdateMethods(UserMethods):
 
     async def _dispatch_update(self, update):
         if self._events_pending_resolve:
-            # TODO Add lock not to resolve them twice
-            for event in self._events_pending_resolve:
-                await event.resolve(self)
+            if self._event_resolve_lock.locked():
+                async with self._event_resolve_lock:
+                    pass
+            else:
+                async with self._event_resolve_lock:
+                    for event in self._events_pending_resolve:
+                        await event.resolve(self)
+
             self._events_pending_resolve.clear()
 
         for builder, callback in self._event_builders: