--- Lib/rlcompleter.py	2014-08-05 15:21:58.000000000 +0100
+++ Lib/rlcompleter.py	2014-08-05 16:58:28.000000000 +0100
@@ -105,7 +105,7 @@
             for word, val in nspace.items():
                 if word[:n] == text and word != "__builtins__":
                     matches.append(self._callable_postfix(val, word))
-        return matches
+        return list(set(matches))
 
     def attr_matches(self, text):
         """Compute matches when text contains a dot.
@@ -130,13 +130,13 @@
             return []
 
         # get the content of the object, except __builtins__
-        words = dir(thisobject)
+        words = set(dir(thisobject))
         if "__builtins__" in words:
             words.remove("__builtins__")
 
         if hasattr(thisobject, '__class__'):
-            words.append('__class__')
-            words.extend(get_class_members(thisobject.__class__))
+            words.add('__class__')
+            words.update(get_class_members(thisobject.__class__))
         matches = []
         n = len(attr)
         for word in words:
@@ -147,10 +147,10 @@
         return matches
 
 def get_class_members(klass):
-    ret = dir(klass)
+    ret = set(dir(klass))
     if hasattr(klass,'__bases__'):
         for base in klass.__bases__:
-            ret = ret + get_class_members(base)
+            ret.update(get_class_members(base))
     return ret
 
 try: