MYSQL error while saving panels

Sometimes when i save my panel settings i get the following error

user warning: Duplicate entry '0' for key 1 query: INSERT INTO panels_pane (pid, did, panel, type, subtype, configuration, cache, shown, access, visibility, position) VALUES (0, 18, '', '', '', 'N;', 'a:0:{}', '1', '', '', 0) in /var/www/drupal/includes/database.mysql.inc on line 172.

although everythin still works fine after this.. still i'm wondering if its a bug..