These are obverse and reverse die trials for the 1903 two Louisiana commemorative gold dollars struck on a single piece of cardboard.
Pollock gave this trial two numbers, P3512 for the obverse and P3515 for the reverse not knowing that both obverse and reverse were on the same piece of cardboard. They really should only have one number.
Only 2 examples are known. The illustrated example is ex Bowers and Merena's 11/97, B/M 2003 ANA, ANR 6/05, Heritage July 2008 ANA, Mike Byers and contains both obverses, Jefferson and McKinley and a single pattern reverse design. The second contains both obverses and six different reverses and is in the Smithsonian. To view this trial piece, click here.
All of these are believed to have come from the Nagy collection.
Photo courtesy of Mike Byers.