2912B Die Cut Shoulder Types

In reviewing several 2915B Juke Box stamps, there appears to be two different die cut corner shoulder types. The stamp on the left below is more rounded and the right more angled/square. Top left corners are similar for each. A friend inform me that he thought only round shoulders have been found. I also have used samples of both types so they don't appear rare. The left one is interesting from the point of view that it is lightly tagged.


The two shoulder varieties above appear similar to the 2904B shoulder types illustrated in the July 11 Coil Line.


I believe the angled type is considered a square shoulder for 2904B. Are these just normal variations or two different shoulder types?

PNC3 recognizes two different shoulder types

Peter

Thanks