Hi Brian
This is not a bug.
When tasks are assigned to a group queue, members of the group receive an email notification if the administrator has turned on the Group - Task Assignment setting on the Task Notifications page.
Once the task is claimed, it is assigned to a individual user's queue.
That individual will also receive an email notification if the Administrator has turned on the Task Assignment setting on the Task Notifications page.
If you turn off the Task Assignment setting to stop the personal queue email, you will be turning off individual assignment notifications globally on the server.
Diana