Although described as regular dies trial pieces, these off-metal pieces were actually deliberately struck for sale to collectors.
Copper examples J587/P652 as illustrated above were issued as part of complete copper sets. One set was in the famous Garrett collection and was sold by Stacks in 1976 and a double set was apparently stolen from the Iowa State Historical Museum. About a half dozen are known.
Examples were also struck in nickel J588/P653 with only 2 or 3 known one of which is illustrated below.
Judd also lists these as being struck in silver-nickel J589 but we believe these are actually the same as the nickel pieces above.
Photos courtesy of Superior.