Do I have to pay for Mountain Lion twice?

[(vikm)]

It wouldn't show up any longer on the computer if it was installed, i don't think. Once installed, i believe it disappears.

I don't know if it would show up on the other computer under purchases once logged in via that machine. It may only show on the original machine that you installed it on.

Again, i could be wrong. Go on, roll the dice and try and d/l it again