64 Dart GT vs 270 interior door emblems?

I've noticed before that my GT door emblems have different part numbers with model next to that part number on the back side. The one plate has valiant,signet,dart 270,dartgt. The plate is universal they just attach the proper center plate for plymouth or dodge. I've never seen a plate that said Dart 270 either, but why is it stamped on the back side of these then. I'm not positive my plates are the originals and maybe later years this was offered in other models. Did your plates have the same stampings on the back side I'm refering to?? Jayson