Is this mint mark a result of doubling or is it something else? It is much thicker than on others I have from the same year and mint. I've attached a pic of the one in question as well as another from same year/mint to compare.
Note the affected area is on the outside part of the devices. (like Machine Doubling) but I don't see any other devices affected, so I feel it is coin contact on that area. But not a RPM, as the overall size of the mintmark is there, but reduced because of the contact area.