MD is not an error such as legitimate die doubling. It is caused by mechanical means and not a part of the engraving on the die.
MD is caused by the the press itself. One of the dies is loose, and when the strike is made, the die "bounces"and some of the metal on the devices can be "plowed" to make a flat and shelflike "doubled" area.
It is common and adds no value.
The slabbed Half dollar No G farce: Download No-FG half vs. Grading Company Claims report here:
https://tinyurl.com/yalrstjz or higher resolution version:
https://tinyurl.com/y7rksxu8- How much squash could a Sasquatch squash if a Sasquatch would squash squash?