Remember this. If you see this on a coin, then look at Liberty. If you see the same thing, but on the left side of Liberty, it is
Die Deterioration Doubling. Deterioration is all on the sides of the devices that are closer to the closest rim. Another point, on the single squeeze dies, the
DDD shows on the field, not on the devices.
Machine Doubling affects the devices, damaging the devices after the strike. This will help you in the search on coins you encounter.