2018 Penny Damage Confusion

You are correct. It is Machine Doubling. The reverse is showing a bit of Grease Fill on the upper letters. But sometimes it is not a Struck Through Grease issue, but a lack of metal movement on the reverse. Very common on Memorial cents and shield cents as well. Neither is a premium for them. Just a distraction. On the shield cents watch for enlargement of the devices. Some remind me of an over inflated bicycle tube.

They start looking like these, that is what your looking for. The devices are distorted from hub doubling.

To confuse even more (your getting it though) When you mentioned the EPU. On the shield cent that area is incuse now. Not raised. When when something is struck into incuse, those devices are raised on the die and make an incuse device on the coin. So when Machine Doubling happens on these incuse devices, a doubled die is reduced in size on them.
Here is a machine doubled EPU

Here is a normal set and a doubled die:



How do I know that is what happens? The raised devices on this coin are all showing enlarged devices.




Hope this covers your questions, if not ask again.

On the ATB Quarters the devices on the outside ring on the reverses have incuse devices in that ring area. About 70% of these have Machine Doubling slight or strong, but as with other machine doubled coins, they don't warrant a premium. People may sell them, but they are not doubled dies.

Thank you! I've been watching your Youtube videos and subscribed. I appreciate your help!