2013 SP1 unexpected behavior when re-assigning a case

Hello all, 

The following steps appears to display some odd behavior:

• Create a case 
• This creates a queue item in a support queue via a workflow so users can monitor the queue 24/7
• Re-assign the case to a new owner 
• The 'Queue Item' now belongs to the new owners queue instead of just staying in the support queue!!! 

For a moment I thought this was standard behavior but now I think it is a bug. I have tried to replicate this behavior in other systems and cannot manage it. The system this occurs on is CRM 2013 SP1 on Premise. 

No Javascript, business rules, additional workflows or plugins. 

Any help would be greatly appreciated.