1968-1972 cents had a lot of
Machine Doubling. They are common to find. The 1969-S
DDO is also know for have
Machine Doubling on a doubled die. The machine causes the MD, the doubled dies are on the die. Thus MD can be found on a doubled die:

Note these 4 from PCGS that show they are all the DDO-001, but see the yellow arrow. That points to where the machine altered the devices right after the strike.