Although these are described as regular die trial pieces in the standard references, it is more likely that the off-metal 'trials' of this year were deliberately struck for sale to collectors.
Examples were struck as follows:
Copper J1102/P1238 with only 4 or 5 are believed to exist including the illustrated example above courtesy of Superior.
Aluminum J1103/P1239 with only 2 or 3 believed to exist.
Nickel J1104/P1240 which is believed to be unique and is ex Woodin, Newcomer, Lohr, ANR 8/04, Stacks 1/08, Simpson-Heritage 9/20 - PCGS65 and is illustrated below.
Photo courtesy of American Numismatic Rarities.