On a normal die when
Machine Doubling happens, it alters what ever height the die bounces.
Bottom:

Mid:

or top of the devices during coin exiting the machine:


On a doubled die, the outside areas most of the time are not affected, but the whole device will be enlarged and you will see a spread on the center of the devices:

Note the location of the spread on the lower image. Doubled dies will show either notching on the corners or spread with an enlargement of the devices on the center area of the devices:

Note that the outside edges are not affected, just the center area on this one showing the spread.
Machine Doubling alters the outside edges of devices.

Edited by coop
01/10/2020 4:34 pm