The CUCM device which puts the call on hold determines which MOH source file is heard by the caller. So if Device #1 is assigned MOH #1 and puts Caller #1 on hold, and Device #2 is assigned MOH #2 and puts Caller #2 on hold, then yes. No problem.
Alternately, I guess it would be possible to use UCCX to perform some algorithm to track the calls and dynamically play a selected file for calls in queue based on the variable outcome of the algorithm. E.g. If the CallId were an even number, play MOH 2. If the CallId were an odd number, play MOH 1. Doing so would seem pointless however, unless I'm totally missing the point. Would you want to explain what is the business application for performing this request please? Thanks