Querysets are now lest restrictive when querying duplicate fields (#332, #333)

mongoengine/queryset/visitor.py

@@ -26,6 +26,7 @@ class QNodeVisitor(object):
 class DuplicateQueryConditionsError(InvalidQueryError):
     pass
 
+
 class SimplificationVisitor(QNodeVisitor):
     """Simplifies query trees by combinging unnecessary 'and' connection nodes
     into a single Q-object.
@@ -39,6 +40,7 @@ class SimplificationVisitor(QNodeVisitor):
                 try:
                     return Q(**self._query_conjunction(queries))
                 except DuplicateQueryConditionsError:
+                    # Cannot be simplified
                     pass
         return combination
 
@@ -127,8 +129,7 @@ class QCombination(QNode):
             # If the child is a combination of the same type, we can merge its
             # children directly into this combinations children
             if isinstance(node, QCombination) and node.operation == operation:
-                # self.children += node.children
-                self.children.append(node)
+                self.children += node.children
             else:
                 self.children.append(node)