[3.7] Fix duplicating words words. (GH-6296) (GH-6297)

Most of them have been added in 3.7.
(cherry picked from commit bac2d5ba30339298db7d4caa9c8cd31d807cf081)
diff --git a/Lib/asyncio/protocols.py b/Lib/asyncio/protocols.py
index 8904478..dc298a8 100644
--- a/Lib/asyncio/protocols.py
+++ b/Lib/asyncio/protocols.py
@@ -105,7 +105,7 @@
 class BufferedProtocol(BaseProtocol):
     """Interface for stream protocol with manual buffer control.
 
-    Important: this has been been added to asyncio in Python 3.7
+    Important: this has been added to asyncio in Python 3.7
     *on a provisional basis*!  Consider it as an experimental API that
     might be changed or removed in Python 3.8.
 
diff --git a/Lib/idlelib/idle_test/test_editmenu.py b/Lib/idlelib/idle_test/test_editmenu.py
index 17eb25c..1747847 100644
--- a/Lib/idlelib/idle_test/test_editmenu.py
+++ b/Lib/idlelib/idle_test/test_editmenu.py
@@ -1,6 +1,6 @@
 '''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')
diff --git a/Lib/idlelib/idle_test/test_text.py b/Lib/idlelib/idle_test/test_text.py
index a5ba7bb..0f31179 100644
--- a/Lib/idlelib/idle_test/test_text.py
+++ b/Lib/idlelib/idle_test/test_text.py
@@ -9,7 +9,7 @@
 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.