Extensions or Deviceanduser with Aastra XML and HotDesking

Right now we are running the FreePBX Distro with version 2.10 and the Aastra XML scripts 2.3.1 that is in the FreePBX yum repository.

We are in Extensions mode, and have users currently HotDesking, i.e. logging into a phone in our call center, which is supposed to log them out of their desk phones.
What I am noticing is that for many of them, they log out, and their phone they log into is able to place calls, however it is hit or miss if they are able to receive them. I also notice repeated registrations in the /var/log/aastra/full from either phone.
What I think is happening is that even though their screen on their desk phone shows “logged out” and they are in fact “logged in” to the phone in our shared call center, the desk phone still stays register and the repeated registrations I see in the log are from either phone essentially fighting over registrations.

I notice that this all goes away if I have them 1st log out of their desk phone, then press the reboot soft-key. Then after that it’s safe to log in to one of our call center phones and everything works reliably.

My Question is, is this the default behavior for extensions mode?
Would switching to device and user mode give us any more reliability?

Is the endpoint staying registered even though logged out a “Bug?”

These are 6737i’s with Beta firmware, so… have to take that into consideration I suppose.