AD Hoc misunderstanding

I think I might have misunderstood when I was shopping. I thought that 2 psps could play multiplayer games with only one UMD. Is this correct or did I read something wrong? Do we need 1 UMD or both need a copy of the UMD.AD Hoc misunderstanding
Some games require one UMD, some don'tAD Hoc misunderstanding
You both need a copy aside from a few select games.
The only game I know of that will work with 1 UMD is tekken. Just go to Game sharing and boom!