During ww2 England and America were allies with the soviet union and stalin was even reffered to as uncle Joe

This is not revelation. The US had to rely on Stalin's help to defeat the Nazis. Allies aren't necessarily friends. Roosevelt and his administration fed the moniker to the Western press in an effort to soften the image of Stalin in order to help make the medicine of and alliance with Russia palatable.

Neither moniker seems to have any bearing on the other.