When creating new course groups (with new parent) the action is not completed (it seems). When aborting the action after 15 minutes the groups appear to have been made anyway. And what's more: Being impatient I clicked the 'maak' button 3 more times.
This resulted in having the same group structure 4 (four) times; With identical names.
In none of the groups users were automatically subscribed (not in parent, not in offspring)
Occurred in Test EVH
ie9, win 7