gh-104269: Document glob.glob duplicates when using multiple ** patterns

Doc/library/glob.rst

@@ -77,6 +77,10 @@ For example, ``'[?]'`` matches the character ``'?'``.
       Using the "``**``" pattern in large directory trees may consume
       an inordinate amount of time.
 
+   .. note::
+      This function might return duplicate path names if *pathname*
+      contains multiple "``**``" patterns and *recursive* is true.
+
    .. versionchanged:: 3.5
       Support for recursive globs using "``**``".
 
@@ -96,6 +100,10 @@ For example, ``'[?]'`` matches the character ``'?'``.
    .. audit-event:: glob.glob pathname,recursive glob.iglob
    .. audit-event:: glob.glob/2 pathname,recursive,root_dir,dir_fd glob.iglob
 
+   .. note::
+      This function might return duplicate path names if *pathname*
+      contains multiple "``**``" patterns and *recursive* is true.
+
    .. versionchanged:: 3.5
       Support for recursive globs using "``**``".
 

Misc/NEWS.d/next/Documentation/2023-06-06-21-18-14.gh-issue-104269.uP1hVC.rst

@@ -0,0 +1,3 @@
+Mention that :func:`glob.glob` and :func:`glob.iglob` may return duplicate
+path names if multiple ``**`` patterns are present and ``recursive`` is
+true.