These 2 found together would make sense if they were found in a part of Poland that belonged two both, Prussia and Poland in different periods of time. One could also imagine that these Grosz coins were also used to pay under Prussian reign, as Prussia also minted grosz coins of copper in some years back then. The area of todays Poland is really interesting from a numismatic point of view as there have circulated coins minted from Russia, Prussia, Poland and also the Free City of Danzig.