Although described as regular dies trial pieces, these were actually deliberately struck for sale to collectors as part of complete sets.
Examples were struck as follows:
Copper J769/P854 with about a half dozen known.
Aluminum J770/P855 with about a half dozen known.
Nickel J771/P856 which is believed to unique and is ex Woodin-1914 ANS exhibit, Newcomer and last offered in ANR's 6/06 sale.
Photo courtesy of Heritage.