The yellow back and rack marks like those are what would concern me most. A person would be able to add grommets to an original sign, I don't know why they would, but it's certainly a possibility so one can't base authenticity on the grommets alone. Usually though, like Dan said, MC-AX plates have white ones. The ones on this plate sure look new and are certainly poorly applied. The M in the MC-AX on my plate is not the same style/font as the one on the sign in question.
I've never seen a reproduction of this particular size and style plate, but there's always got to be a first. This particular shield from the Magnolia marketing territory has always been questioned by newer collectors especially, due the the larger size and thin border. They usually only think of the wider blue border 12X12 inch plate variations as being the only "real" plates. I wouldn't think it would be a popular candidate for repros, but if there's a dollar to be made these days......
