A/C question

[2 DA WDS]

I have an 05 RE3 with 2 A/Cs. The rear one is the 15000 w/ heat pump and the front one is the 13000. If I have both of them turned on the majority of the time the front one runs. This makes sense to me because the front being higher would tend to have the hotter air. But if this were the case shouldn't the front air be the higher BTU?
Is this the case with other units? I didnt notice this in our other RE3 but then we had a sensor in the rear and this unit doesn't and we were seldom on 50 amp with the other one so we mostly ran one at a time.
Just sitting here wondering.