This is one of several sites that will help you learn about the different kinds of doubling on coins: https://doubleddie.com/144801.html Doing some research is part of the fun in collecting coins.
DDD. Education is a wonderful thing and the members here have taught me a thing or 100, but the best info is to do research as @thomas mozzillo points out. I find more than what I was looking for which leads me to another issue I thought I knew a lot about. Turns out I was a novice about some aspect related to judging coins.
Not an opinion but the correct answer.. Not MD but as the others stated DDD Here is a reference on DDD even showing a 1989 Cent - http://www.error-ref.com/die-deterioration-doubling-incuse/
