As long as you learn what you collect I doubt the counterfeiters will win . Where is the other thread ?
Here's a link to the types of MD . http://www.errorvariety.com/OFD/MD.html
There are doubled dies , but they can be confused with common machine Doubling .
If you find one where Lincoln is raised with no mirror lettering you might have something .
Why would you want to remove it ?
Separate names with a comma.