Not sure what you mean by this.
My point, in a nutshell, was, that it seems like if Djokovic doesn't stop Roger, e.g. RG 11, then Nadal will. But Djokovic might stop him first. Might not. But one of the two will do, unless Roger doesn't even get that far (RG 10, Wimbledon 10, 11). Always a bit silly to project forward based on the past, but in the last 8 slams Roger hasn't made it to the SF 3 times, been stopped by Nadal twice, and stopped by Novak 3 times. He has enough trouble beating one of them in slams now, beating both seems like a big ask. This assumes all three get that far in the draw but Nadal and Djokovic have been very consistent at doing so this last several slams.
Ok now I understand better : I had missed the "either ... or" in your previous comment, sorry
PErsonally I think that if he has one-day rest between those matches, there's no reason why, having beaten one of them, he could not beat the other one.
That said, I said "if he has one-day rest", and that's very important, because in 2010, Federer didn't know in advance that that one-day rest would be given by the rain before the final hence his feeling that "he had to win quickly against Djokovic" hence the fact that he played with too much offensive against Djokovic in that 2010 match.
Vida said that this sentence proves how much his defeats to Djokovic in USO semifinals have been painful,
personally I think that all he has constantly said about these events is that he was always concerned about winning the tournament first of all, not so much about the semifinal only.