Correct typos in the Barrier specification (GH-9395)

Doc/library/threading.rst

@@ -968,7 +968,7 @@ As an example, here is a simple way to synchronize a client and server thread::
       Return the barrier to the default, empty state.  Any threads waiting on it
       will receive the :class:`BrokenBarrierError` exception.
 
-      Note that using this function may can require some external
+      Note that using this function may require some external
       synchronization if there are other threads whose state is unknown.  If a
       barrier is broken it may be better to just leave it and create a new one.
 
@@ -976,7 +976,7 @@ As an example, here is a simple way to synchronize a client and server thread::
 
       Put the barrier into a broken state.  This causes any active or future
       calls to :meth:`wait` to fail with the :class:`BrokenBarrierError`.  Use
-      this for example if one of the needs to abort, to avoid deadlocking the
+      this for example if one of the threads needs to abort, to avoid deadlocking the
       application.
 
       It may be preferable to simply create the barrier with a sensible