Although described as regular dies trial pieces in the literature, it is more likely that these were deliberately struck for sale to collectors.
Examples are known as follows:
Copper-nickel J458/P532 with only 2 or 3 known.
Nickel J459/P533 with only 2 or 3 known. One was offered in Bolender 11/35 lot 178.
One of each was in the J.E. Drew collection including the one illustrated above.