In some maps there is a bug like this:
http://www.prikachi.com/images/355/6184355w.jpg
Player 1 duck and player 2 jumps on him,then player 1 starts to jump and player 2 is transferet from the wall on the second floor.How to fix this map bug?Could i place a solid invisible entity in the wall so the player could not transfer in second floor?If it can how to do it,pls help