Can we make it so you can't re-roll into the champion you just had...

I was playing an ARAM the other day, got a champ I didn't want to play (Galio I think). I had two rolls and no interest in playing him. So I rolled and got Skarner. No thanks. So I used my last roll and... what do you know, it was Galio again. I understand this almost never happens... but it shouldn't be able to happen -.-