It may just be machine doubling. I don't think they tried to align them that carefully on the proofs for fear of messing up the die. I looked at the 6 - 71S that I have, and the mintmarks are in three different places. Chris
Nope. Proof coins get struck at least 2 times. Any movement during any of the strikes will leave ghost markers such as what you're seeing. Consider it kinda like a squashed flat mintmark. This is actually quite common on the 1971-S Proof IKE's. The shelving you see on the west part of the mm is nothing more than machine doubling which is also quite common on these coins.
