Breakthrough Liberation Peak - Attackers have 4 tanks

Yesterday we encountered an interesting game, not sure if this is a non public bug or the action of a cheating player, but the attackers were able to spawn in 4 tanks and as soon as one got destroyed it instantly got replaced. 

As you might have guessed, this made the game super one sided, with no chance for defenders to do anything. (Screenshot of the map, with 4 visible tanks attached)