If there was a perfect play from both sides, but each player was allowed to do 2 moves every time, would white win? Imagine a game where players are allowed 2 moves instead of one. If there were perfect play from both sides, would White win?
This chess variant you are talking about is Marsellais Chess. I infer that you mean that White has two moves to start with. If this was so, White would have an advantage(a refined version of this variant gives White only 1 move on the first move to null the opening advantage). So White would probably win. However, this is not certain, as we have not written a sufficiently strong engine for this yet.