This is a 1977 Jefferson nickel which is a dual-date double-denomination, and is struck on a 1976 Lincoln cent. The cent's date (1976) is about 60% visible, and is clearly defined. The error occurred when a 1976 Lincoln cent was fed into a press which was striking 1977 Jefferson nickels, and was struck. Dual date double-denominations are very rare, especially on nickels (although rare, they're much more common on cents on dimes.)

NGC MS-64 RB with beautiful, lustrous surfaces.