Although listed as a regular die trial piece, these were more likely deliberately struck for sale to collectors as part of complete aluminum sets.
Only 2 examples are believed to exist as follows:
1) Farouk, Kosoff 66 ANA, B/M 10/87, Superior 10/89
2) Stacks 76 ANA
Photo is actually a color enhanced regular proof example which approximates what the real trial piece looks like and is courtesy of Heritage.