Fix duplicate word.

Doc/library/heapq.rst

@@ -95,7 +95,7 @@ The module also offers three general purpose functions based on heaps.
 
    Merge multiple sorted inputs into a single sorted output (for example, merge
    timestamped entries from multiple log files).  Returns an :term:`iterator`
-   over over the sorted values.
+   over the sorted values.
 
    Similar to ``sorted(itertools.chain(*iterables))`` but returns an iterable, does
    not pull the data into memory all at once, and assumes that each of the input