Threaded crank arms

Hmmm, I don't suppose you tried to screw the left pedal into the right crank and vice versa? You know that the left has a reverse thread, don't you?

I'm slapping myself on my forehead as I think I may have done this :S

I'm new to the whole bike building shenanigans so its more than likely! Any chance if I swap the pedals around and re-tap them that way it would work? or are the thread likely to be too far gone?