I've seen a few of the local randos with two computers, usually mounted -- quite ingeniously I thought -- to the same fork, in opposite directions, so that both run off the same magnet.

I opted instead for the Cateye Enduro which has two odometers; therefore, I hope I can zero one of them while keeping a running total on the other.

But is it standard to run two computers, not just for zeroing at turns, but in case one breaks down?