diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 994d0273f..79036e9c8 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -1100,6 +1100,9 @@ class ModelSerializer(Serializer):
         fields = self.get_default_field_names(declared_fields, info)
 
         if exclude is not None:
+
+            # make sure all fields are unique
+            fields = set(fields)
             # If `Meta.exclude` is included, then remove those fields.
             for field_name in exclude:
                 assert field_name in fields, (
@@ -1112,6 +1115,8 @@ class ModelSerializer(Serializer):
                 )
                 fields.remove(field_name)
 
+            fields = list(fields)
+
         return fields
 
     def get_default_field_names(self, declared_fields, model_info):