This is a fascinating multiple mint error. The reverse of this 1966 Lincoln Cent has a first strike mirror brockage of the obverse design. The coin rotated in the collar and was struck again. Detail is visible on the obverse from the rotated double struck design including Lincoln, the date and some of the lettering. The 1966 date is visible on the reverse from the first strike mirror brockage that was overstruck by the reverse Cent die.

Mirror brockages are scarce in the Lincoln Cent series but a mirror brockage which was double struck is extremely rare. This mint error was discovered out of an old-time collection and was authenticated and certified by CAC.

Detail is visible on the obverse from the rotated double
struck design including Lincoln and some of the lettering:




The 1966 date is visible from the first strike mirror
brockage that was overstruck by the reverse Cent die:




Brockages are featured in my NLG Award winning book,
World's Greatest Mint Errors.