1972 Lincoln Cent
Struck Over Struck 1971 Lincoln Cent
PCGS MS 62 BN

This type of error is known as a dual-date overstrike. A struck 1971 Lincoln Cent was overstruck by 1972 Lincoln Cent dies.

It is a very rare type of error when a dual-date overstrike occurs on the same denomination.

Overstrikes are featured in chapter 19 of my
NLG Award winning book, World's Greatest Mint Errors: