Keep in mind that
Machine Doubling can experience different heights of the MD. Low/medium/high bounces. Also it can be in a single or more direction or even a swing direction. Depending on how loose the machine is, it can be different on each strike or follow a pattern. The only rule for
Machine Doubling is that there are "No Rules." It happens because of the loose part of the machine. But it appears in certain ways:
1. It always affects the devices on one side of the devices. (top/bottom or right/left side of the devices)


2. It always affect the outside/insides of devices removing the contour that was there, before the machine did happen. (if you see on the one side of the devices, the opposite side will be normal, unaffected.



3. A doubled die comes from a "doubled die." A doubled die coin can have
Machine Doubling on them altering the coin, but
Machine Doubling never creates a doubled die on a coin. A doubled die only comes from a die what has hub doubling on the die.

Note the date is hub doubled, the yellow arrows are pointing to the machine doubled areas. Note the
DDO enlarged the devices, the machine doubled area is flat, a reduction of the device that was there on the coin before the
Machine Doubling happened.
4. If a doubled die has
Machine Doubling, it is less desirable to a seasoned collector. It is a distraction to a doubled die. Thus they may dismiss it because of the MD. Hope this helps.
The sad part of the 1969-S
DDO's, is that they are mostly
Machine Doubling on the doubled die. Thus ruining the affect of the doubled die. But it happens.
CoopHome:
Machine doubling: Does it have rules it follows? Why are they less desirable to to a seasoned collector?