What is the difference between Machine Doubling and a doubled die?:
On your coin, what you are looking at is the alteration of the devices. (Pushed metal that happen by the machine after the strike.
How can we tell?
Note the tape on these two images. Note the example on the right, you can see the flat area that altered (reduced) the size of the devices. On the image on the right, you can see where there are two raised areas on the devices. Note the tape how it flows over the two raised areas? This is called spread. The distance between the hub that created the die, made these doubled devices. That is why they are called a doubled die. The doubling is on the die.
Machine Doubling is from a normal/or a doubled die that flattens part of the devices, leaving the look like a fender bender on your car. The damage is always pushed in from where the original area was curved. (Same as on your car) Here is a side by side to show how the same is pushed into the normal size:

Note on your coin, the same area is affted on the 'O' on ONE, just like your coin on the image on the left. The center image is a regular sized device. Note how the MD reduced the size of the devices on the altered areas. The image on the right is showing hub doubling with the spread between to two sets of images.
1.
Machine Doubling is damage caused to the devices right after the strike. (on the way up off the coin) This movement damages like a kick in the shin, quickly after the strike. (Just like a fender bender)
2.
Machine Doubling reduces the size of the device, even smaller than normal devices.
3. The contour is removed from
Machine Doubling. The ability of light to fade from lighter to dark, is gone. Now the light is reflected shiny, and if the light is at a different angle it doesn't fade, it falls over the cliff of the damaged area.
4.
Machine Doubling occurs on the outside edges of the devices. On a doubled die the spread is in the centers of the devices.
5. Hub doubling creates doubled devices. Either small or very large. You can see spread between the hubbing of the die. In the corners of a doubled die you can see notching. (another indicator of a doubled image)

Need more images I could provide these. Hope this helps.
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Machine Doubling doubled die differences Chuck