When you roll a champ in ARAM, you shouldn't be able to re-roll that same champ again.

I rolled kassadin, didn't want him so I rolled again and got Aurelion Sol. Somebody wanted to trade and so I gave them the dragon and then I got xin in trade. I didn't want to play Xin so I used my second roll and rolled kassadin...again.

Seriously, if you roll a champ there is a REASON for it, don't waste a roll for us by giving us the champ we just rolled...