diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index 7400fb7..aeea2aa 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -2199,6 +2199,15 @@ def create_autospec(spec, spec_set=False, instance=False, _parent=None,
         except AttributeError:
             continue
 
+        # If our autospeccing already created this attribute through
+        # _setup_func above, skip it!
+        if (
+                hasattr(mock, entry) and
+                hasattr(spec, 'mock') and
+                hasattr(spec.mock, '_mock_delegate')
+        ):
+            continue
+
         kwargs = {'spec': original}
         if spec_set:
             kwargs = {'spec_set': original}
diff --git a/Lib/unittest/test/testmock/testpatch.py b/Lib/unittest/test/testmock/testpatch.py
index dfce369..62fdca2 100644
--- a/Lib/unittest/test/testmock/testpatch.py
+++ b/Lib/unittest/test/testmock/testpatch.py
@@ -1843,5 +1843,23 @@ class PatchTest(unittest.TestCase):
             self.assertEqual(foo(), 1)
         self.assertEqual(foo(), 0)
 
+
+    def test_double_patch_instance_method(self):
+        # See http://bugs.python.org/issue26704
+        class C:
+            def f(self):
+                pass
+
+        c = C()
+
+        with patch.object(c, 'f', autospec=True) as patch1:
+            with patch.object(c, 'f', autospec=True) as patch2:
+                c.f()
+            self.assertEqual(patch2.call_count, 1)
+            self.assertEqual(patch1.call_count, 0)
+            c.f()
+        self.assertEqual(patch1.call_count, 1)
+
+
 if __name__ == '__main__':
     unittest.main()