If the Group was created first than the registered user with the same name, if you perform adminp delete on the user it will also delete the Group document with the same name.
Create a group named "John Doe", after creating this group (regardless of the type) you can Register a user with the same name. If you perform adminp delete on user John Doe, it will also delete the group with the same name.
However, if you register the user first as "John Doe" you will not be able to create a new group named "John Doe" because a prompt will appear that a same name exists.
This has been raised under SPR CKHO53FMS9.
Can we have at least the same prompt if we are registering the User that the same name is already being used as a group name?
This will prevent in creating Users and Groups having the same name.