Here are just two examples of one trim code on the door tag and a different trim code on the buck tag:
http://www.specialservicemustang.net...info122743.htm
http://www.specialservicemustang.net...info182331.htm
Not sure why "G" code was on the buck tags though. That code hadn't been used since 1989, and then it was for A/S leather seating (convertibles only), not 'base' cloth seating.
I think I have only seen this alternate trim code between the door tag and buck tag in 1991-93, when LX 5.0L sedans were supposed to have a A/S seating standard.