20 Zlotys 20th Anniversary of People's Republic of Poland, Trial Strike CuNi

In 1964, Polish state authorities commissioned commemorative 20-złoty pieces marking two decades of the Polish People's Republic. Trial strikes — próby — in copper-nickel were produced alongside other experimental compositions as part of the standard approval process run through the Warsaw Mint. Most never entered general circulation; they exist today almost exclusively because mint employees and party officials retained examples outside official channels. The Fischer and ParM catalog references both distinguish this CuNi trial from the aluminum and other compositional variants struck in the same approval run.