The so-called regular dies trial piece in copper. It was more than likely deliberately struck for sale for a collector.
This is much rarer than the transitional pattern J452-J453/P524-P527 with only the following 2 confirmed.
1) Bolt-Stacks 4/66, unknown intermediaries, Simpson collection - PCGS66RB, illustrated above courtesy of PCGS.
2) Kagin 1/75?, B/M 6/88, Heritage 1/01 - PCGSVF25, illustrated below of Heritage.
Others are likely from A.S. Jenks (1877), Parmelee (1890), Stickney (1907), Woodin 1914 ANS exhibit, Curtis (1950) and Farouk (1954).