It looks like someone spliced into the direct wire connection from the Gen to the AC control switch panel. Installed an outlet and plugged wire back into the outlet. I assume for a outside outlet for whatever might be needed when not in a campground.
With Gen set running and AC switch set to Front AC, the front AC will run and the back AC will also run. This is not the case when plugged into Shore power.
Unplug the small plug in the outlet and the rear AC does not run unless the switch is set to Rear.
thanks to all who replied and your Ideas. And to this great resource forum for the diagrams etc.
I will definitely be back and try to help others if possible.