Notification System sends exact same SQL query multiple times

The following query is executed more than once on http://localhost/projects/phpbb3/phpBB/ucp.php?i=ucp_notifications&mode=notification_options

SELECT group_id

FROM phpbb_user_group

WHERE user_id = 2

AND group_leader = 1

LIMIT 1

Seems to be sent from ./phpbb/notification/type/group_request.php