Although called a regular dies trial piece in the reference works, this was more likely deliberately struck for sale to collectors as part of complete off-metal sets.
Examples are known as follows:
Copper J790. This is unlisted in Pollock. If any do exist, they are probably masquerading as a regular issue proof.
Aluminum J791/P877 with fewer than 3 confirmed including the illustrated piece above from Heritage 8/14 sale.
Nickel J792/P878 with fewer than 3 known including the piece illustrated below.
Silver-copper J793/P879 with planchets produced such that one side is primarily silver and the other primarily copper. Fewer than a dozen are known with examples mixed with regard to which side is silver and which side is copper. These are said to have been struck from native Michigan ore according to Judd.
Photos courtesy of Heritage.