Board Thread:General Discussion/@comment-5821891-20131031221624/@comment-32390199-20150402195738

Although we don't know exactly if this also applies to OUaTiW, the original story of Lewis Caroll lets Alice go to Wonderland 2 times. In her first visit the Queen of Hearts was the 'main antagonist' while in Through the Looking Glass, the Red Queen was.

And it is heavily implied in Once that all the events of young Alice happened almost the same, so it is safe to assume that Alice went there twice.