asterisk users - Apr 2005 - Dynamic queue member behaviour

I found that if I dynamically add, for example SIP/8000, to a queue,
then calls in the queue will sorta pile up on the 9 extensions on that
phone - not what we want to happen.

If I log in to the queue using AgentLogin, then the behaviour is as
expected - one call at a time.

Is there a way around this, or am I adding dynamically to the queue incorrectly?

Thanks in advance for any assistance.