Nickel Doubling Or Machine Or Damage?

that's some sort of doubling, but can't tell which from small monitor photos

Could be either or both? But doesn't matter as it is not a doubled die. Just a battered coin now. Spender. If you are looking for a doubled die, then you are looking for the wrong thing on the coin to show spread on a doubled die:

Note the devices on the DDR? How the devices are wider, not reduced like on your coin. The flat push on the '0' is Machine Doubling, on the 'B' the device has taken a hit. Now look again at the doubled die I posted. Look at the centers of the devices. Note they are wider/taller than a normal coin? You coin was from a normal die and was altered post strike. ( Machine Doubling) and coin contact. Neither are a plus for the coin. Spender. Want answers to questions you not thought of yet? Look at the 'Sticky area" on this site. Click on the link with 1-20 numbers on that second. Start at 20 and go back, and read each thread there. You will treat you brain and eyes to a visual feast. You will be able to see and read what you are looking at on coins.

very helpful is an image editor that lets you choose jpg compression ratio, then you can up the compression to make the file size smaller

Please no photos of monitor screens, use a memory card in your scope. With that pic it looks like MD not a doubled die.
John1