The regular dies trial piece. These were likely deliberately struck for sale to collectors.
Examples were struck as follows:
Copper J421/P493 with fewer than 4 confirmed. An example is in the Connecticut State Library.
Nickel J422/P494 with only one known. This piece was first sold as lot 830 in Mason & Company's February 1871 sale. It more recently appeared in a January 27, 1997 Coin World ad by Delaware Valley Rare Coins and then in Heritage 4/98 fixed price list in a PCGS63 holder.
Photo courtesy of American Numismatic Rarities.