It is a form of Machine Doubling. Note how the bottoms of the devices are not enlarged. This would happen on a doubled die. Also a larger area would have been affected. The one mentioned on Potter's site if from die wear. The 75% copper in the Nickels are not the problem. The Nickel content makes the dies wear faster, but in the area between the outside rim and the devices near the rim. I do see a LDS coin in the image because of the die flow between the devices in the image of the OP.




















