Doc: remove duplicate word in controlflow tutorial (GH-16163)

(cherry picked from commit b7af4e75657e6478920d00260c48a1a3020002fc)

Co-authored-by: Adorilson Bezerra <adorilson@gmail.com>
diff --git a/Doc/tutorial/controlflow.rst b/Doc/tutorial/controlflow.rst
index b7e003c..3730a21 100644
--- a/Doc/tutorial/controlflow.rst
+++ b/Doc/tutorial/controlflow.rst
@@ -695,7 +695,7 @@
 * Use keyword-only when names have meaning and the function definition is
   more understandable by being explicit with names or you want to prevent
   users relying on the position of the argument being passed.
-* For an API, use positional-only to prevent prevent breaking API changes
+* For an API, use positional-only to prevent breaking API changes
   if the parameter's name is modified in the future.
 
 .. _tut-arbitraryargs: