Apparent doubling as a split upper serif with doubled upper loop resembling an RPM. This is due to a damaged punch and not a true RPM. Further information can be found in Will Brooks' Coin World article (November, 2018 with photos by Ray Parkhurst) entitled “Defective punches for Mint marks can deceive collectors” as well as at Variety Vista. Both the original 1974-S WRPM-001 and WRPM-002 listings were found to be the damaged punch.