I'm asking questions because you're leaving out details that people need to answer
If it was a patch, you would hear it on both talkgroups. I'm fairly positive MPSCS would not allow a 24x7 patch of two talkgroups, so that's pretty much a non-starter. Since they are owned by the same company, why is it hard to believe that they would both dispatch off the same talkgroup? Do they use totally different names or unit designators? They just spent half-a-million on a dispatch center, so doing more than one of their sub-companies seems like a plausible option.
But a 24x7 patch of two talkgroups on MPSCS? Doesn't.