[3.6] Fix duplicating words words. (GH-6296) (GH-6298)

Backport idlelib duplications.
(cherry picked from commit bac2d5ba)

Lib/idlelib/idle_test/test_editmenu.py

 '''Test (selected) IDLE Edit menu items.
 
-Edit modules have their own test files files
+Edit modules have their own test files
 '''
 from test.support import requires
 requires('gui')

Lib/idlelib/idle_test/test_text.py

@@ -9,7 +9,7 @@ from _tkinter import TclError
 class TextTest(object):
     "Define items common to both sets of tests."
 
-    hw = 'hello\nworld'  # Several tests insert this after after initialization.
+    hw = 'hello\nworld'  # Several tests insert this after initialization.
     hwn = hw+'\n'  # \n present at initialization, before insert
 
     # setUpClass defines cls.Text and maybe cls.root.