Hoy Tom, You have stumbled on to one of the ways you check a trim tag for it being a repro. When a repro tag is ordered you supply all the info to the manufacturer and they stamp it for you. The repro tag is only as good as the numbers supplied. You may ask the question; "Why spend $200 on a repro tag"?
The answer would be; "Because 1st gen Camaros are documented by the trim tag".
As you can see that this tag is being auctioned by Team Camaro. Some Camaro people still don't realize that a Pontiac can be researched through PHS. Sometimes they find out after they buy the tag.......
You have two choices here as to what to believe; It's either a repro or a factory missprint. I'm assuming that your tag is real and you haven't made any mistakes with your math.