Fixed #27073 -- Removed duplicated managers in `Model._meta.managers`.

1 files changed, 6 insertions, 1 deletions

diff --git a/django/db/models/options.py b/django/db/models/options.py
index 670e2a5a2f..38f2fcfefc 100644
--- a/django/db/models/options.py
+++ b/django/db/models/options.py
@@ -369,11 +369,16 @@ class Options(object):
     @cached_property
     def managers(self):
         managers = []
+        seen_managers = set()
         bases = (b for b in self.model.mro() if hasattr(b, '_meta'))
         for depth, base in enumerate(bases):
             for manager in base._meta.local_managers:
+                if manager.name in seen_managers:
+                    continue
+
                 manager = copy.copy(manager)
                 manager.model = self.model
+                seen_managers.add(manager.name)
                 managers.append((depth, manager.creation_counter, manager))
 
                 # Used for deprecation of legacy manager inheritance,
@@ -387,7 +392,7 @@ class Options(object):
 
     @cached_property
     def managers_map(self):
-        return {manager.name: manager for manager in reversed(self.managers)}
+        return {manager.name: manager for manager in self.managers}
 
     @cached_property
     def base_manager(self):