Most doubling products simply mix your dry vocal with the same vocal slightly detuned and possibly with a small static delay. VoiceOne can do that as well, but what’s unique about it is that it can actually dynamically fluctuate both the timing and the pitch of the doubled voice.
It can be a stunningly natural sounding effect because it very closely emulates real life; two singers could never exactly sing exactly in time or pitch with each other (though they may come very close). If you are attempting doubling right out of the box, you’ll need to mix the dry and wet outputs externally.
By externally altering the panning of the two voices, the doubling will sound even better.