I have been working on a quick visual analysis of Other Forms of Doubling (OFD). (This whole page plus other examples have been archived here: LINK.)
Here I have illustrated Die Deterioration Doubling (DDD) on both new and older Lincolns. Illustration a. is a 1989D with DDD that is often mistaken for MD (what I had thought for a time as well) OR for beginners, confused as a Doubled Die. You can see in the first picture that the date has a ghostly doubled companion, by changing the light (photo 2), one can see the typical orange peel associated with DDD on older Lincolns is present here as well. (Also note the mintmark has Split Plating Doubling.) Below for comparison is a 1989P with clear Machine Doubling( (MD) and finally a 1989P 1DO-005 with class VI extra thickness in the date.
Illustration b. shows a common LDS examples of a 1955 with DDD on the second 5 and across IGWT (sometimes called a poorman’s double die, a misnomer) in LIB of LIBERTY and the 4 of a 1954. At the bottom is a 1955 DDO-002 with separation and notching for comparison with a real doubled die.