Note the size of the devices. If they are normal sized and the area on the edge of the devices are reduced, it is not a doubled die, but Machine Doubling
. Thus why I make a side by side comparison to see if the devices are reduced, or enlarged:
See how comparing them with a normal coin helps. Also another clue. Look at the closed in letters like 'O' 'D' the hub doubling makes the centers smaller on doubled dies. Also curved letters will show Machine Doubling
reduction as one side of the device is thinner and the contour is removed by Machine Doubling
. What for these before you have a heart attack. Doubled dies will be easy to spot when you know what to look for.