OMG, people really need a history lesson, even though i have explained this a thousand times...
There were no other entities, there were no legal countries until the Independences in the 90s. Doesn't matter what your ethnicity was, you were under the rule of Russia, doesn't matter if the hat was "Soviet Union". It's not the same as the European Union. They weren't Independent countries.
If that isn't enough, on 31 January 1992, the United Nations recognized, without objection, Russia as legal successor of the rights and obligations of the former Soviet Union.
https://web.archive.org/web/20031123143520/http://www.iaea.org/Publications/Documents/Infcircs/Others/inf397.shtml
If Catalonia succeds in the future from Spain, would you say any medals from Catalonian athletes in the past shouldn't be counted for Spain? No, because at the time when they were won, they were part of Spain.
That's why in the history books Ukraine, Belarus, Armenia etc. and their results are counted after they gained Independence.