I think what you’ve described doing sounds right. If the words are different I would probably put each Volta on a separate parallel but if they are the same, it’s usually clear enough to put them on the same line. I think the main issue is clarity – if you feel that doing B) above is clear and the music is straight-forward then it should be good. If it at all seems unclear as you are proofing it, it’s probably best to braille each Volta separately, as in A).
Hope that helps!