Because you are converting sensitivity within a single game, the scopes FOV/sensitivity is based on the hipfire FOV/sensitivity, so it will always be the same. If you convert from another game with a different hipfire FOV, the result will be different because the scopes will match the other games hipfire and not R6's.
As for the scopes, 0.02 and 50 is the perfect match, you might get some decimals different simply because of lack of decimals.