[3.12] gh-104269: Document glob.glob duplicates when using multiple ** patterns (GH-105406) (#117757)

gh-104269: Document `glob.glob` duplicates when using multiple `**` patterns (GH-105406)
(cherry picked from commit c06be6b)

Co-authored-by: Tomas R <[email protected]>

Author: miss-islington

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 may 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 may return duplicate path names if *pathname*
+      contains multiple "``**``" patterns and *recursive* is true.
+
    .. versionchanged:: 3.5
       Support for recursive globs using "``**``".