fake Khorezm 20/100 rubles
https://www.staraya-moneta.ru/lib/13311/ - article in Russian. See chapter about 1970s. If you have way to run surface metal test, check amount of zinc in alloy. Article tells that fakes are made of brass.
If you decide to collect Khorezm rubles, get a book about them first. You need the way to tell which variant you are buying before paying for it.