Multiple hierarchy doesn't work correctly

Tested on both drupal 4.7.2 and HEAD.
1. I create a container with Hierarchy set to Multiple.
2. When adding a category I get
user warning: Duplicate entry '2-1' for key 1 query: INSERT INTO category_hierarchy (cid, parent) VALUES (2, 1) in C:\!projects\web\drupal47test\includes\database.mysql.inc on line 120.

This happens because the module tries (for unknown reason) to add one more extra child-parent relation between node or category that is created and container.

PS. Sorry if it's duplicate, I've searched for "Multiple hierarchy" in category issues but have not found any similar issue.