Double bans on the same champion in champion select

During the banning phase in champion select I could see a certain champion banned by bouth teams. eventually it showes one of the teams has banned 3 champions and the other has banned 4 champions having a common banned champion in bouth their ban lists.

I used to get many "dissconnected from PVP.net" messages in the lobby and during champion select at that time although I wasn't experiencing any connction issued while playing. I saw This kind of thing twice. once fiora was double banned and the other time Yasuo was on bouth of the banned champions lists. In bouth cases I wasn't the player who was banning. In bouth cases one of the lists had finally 4 banned champions in total.