diff --git a/jsonpickle/unpickler.py b/jsonpickle/unpickler.py
index 8a50dde..5d5df6f 100644
--- a/jsonpickle/unpickler.py
+++ b/jsonpickle/unpickler.py
@@ -690,7 +690,12 @@ class Unpickler(object):
             # implements described default handling
             # of state for object with instance dict
             # and no slots
-            instance = self._restore_from_dict(state, instance, ignorereserved=False)
+            # Update __dict__ directly to avoid double restoration of nested state
+            if hasattr(instance, '__dict__'):
+                instance.__dict__.update(state)
+            else:
+                for k, v in state.items():
+                    setattr(instance, k, v)
         elif has_slots:
             instance = self._restore_from_dict(state[1], instance, ignorereserved=False)
             if has_slots_and_dict:
@@ -708,7 +713,10 @@ class Unpickler(object):
         return instance
 
     def _restore_object_instance_variables(self, obj, instance):
-        instance = self._restore_from_dict(obj, instance)
+        # If we have a STATE tag, defer attribute restoration to _restore_state
+        # to avoid double-processing nested mutable containers.
+        if not has_tag(obj, tags.STATE):
+            instance = self._restore_from_dict(obj, instance)
 
         # Handle list and set subclasses
         if has_tag(obj, tags.SEQ):