diff --git a/Lib/_py_abc.py b/Lib/_py_abc.py
index 4780f9a6199..c870ae9048b 100644
--- a/Lib/_py_abc.py
+++ b/Lib/_py_abc.py
@@ -33,8 +33,6 @@ class ABCMeta(type):
     _abc_invalidation_counter = 0
 
     def __new__(mcls, name, bases, namespace, /, **kwargs):
-        # TODO: RUSTPYTHON remove this line (prevents duplicate bases)
-        bases = tuple(dict.fromkeys(bases))
         cls = super().__new__(mcls, name, bases, namespace, **kwargs)
         # Compute set of abstract method names
         abstracts = {name
@@ -100,8 +98,8 @@ def __instancecheck__(cls, instance):
         subtype = type(instance)
         if subtype is subclass:
             if (cls._abc_negative_cache_version ==
-                    ABCMeta._abc_invalidation_counter and
-                    subclass in cls._abc_negative_cache):
+                ABCMeta._abc_invalidation_counter and
+                subclass in cls._abc_negative_cache):
                 return False
             # Fall back to the subclass check.
             return cls.__subclasscheck__(subclass)
diff --git a/Lib/abc.py b/Lib/abc.py
index 1ecff5e2146..f8a4e11ce9c 100644
--- a/Lib/abc.py
+++ b/Lib/abc.py
@@ -85,10 +85,6 @@ def my_abstract_property(self):
     from _abc import (get_cache_token, _abc_init, _abc_register,
                       _abc_instancecheck, _abc_subclasscheck, _get_dump,
                       _reset_registry, _reset_caches)
-# TODO: RUSTPYTHON missing _abc module implementation.
-except ModuleNotFoundError:
-    from _py_abc import ABCMeta, get_cache_token
-    ABCMeta.__module__ = 'abc'
 except ImportError:
     from _py_abc import ABCMeta, get_cache_token
     ABCMeta.__module__ = 'abc'