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.
In copper, only 4 or 5 are believed to exist.
These were also struck in aluminum J1435/P1578 with only 2 or 3 known.
Note: The die trials of this year are often found gilt due to the rarity of many of the gold denominations.
Photo courtesy of Superior.