Are any of these servers what you are looking for?

Servers with "Double" and "Tank" in the name:
Zomb!e ISLΛNDS 17/20 | DoubleTank | Яewards
ESP | 20VS+Double Tanks | L4D2 | FederacionGamer.com
ESP | 20VS+Double Tanks 2 | L4D2 | FederacionGamer.com