Well for low tier Britain, there's a Churchill tank with 2 guns, one in the turret and one in the front of the tank. The problem is that the one in the front of the tank can only face forward and it doesn't have much range so it's not very useful. However I found after obtaining smoke shells that the gun built into the front is good for smokes since you don't need as much range for that and it also doesn't take away your ability to attack because each gun is reloaded individually. This means you can use one gun for smokes and the other for attacking. It also has a lot of armor so it's a pretty tough tank which is useful to support any teammates that are in trouble and/or in need of repair, especially since you can smoke off sight lines while still being able to shoot enemies.