Re: dual zone windshield defrost question....
The front defrost is a selection, not a switch like rear defrost so pressing it again will have no effect. You need to press Auto or another vent selection to deselect front defrost.
The last few cars I had with auto climate control did the same thing. I've always just press Auto when the window is defogged/defrosted for a long as I can remember.
2012 Grand Cherokee SRT8 Black/Black