Installing Guild Wars on two computers?

I have guild wars on my desktop and now my brother wants to play against me. So I tried installing GW on our laptop and it worked until I got to the create account part. I attempted to use the access keys from my desktop PC, but it does not work because they are already in use... Is there any workaround for this issue, or would we have to buy another set of games?

If you want to have 2 accounts, you HAVE to have 2 sets of keys. You can play the same account on different PCs, but not at the same time.