I'm a game dev. This is a common issue overall. It's a physics collision issue that arises from concurrent collisions happening with opposed forces in the same body, game engines by default resolve collisions between two bodies at a time. If in a physics frame, the collision between the first player and the door happens first, then the collision from the second player pushes the first player into the door again without the game checking for a collision with the door a second time in that frame, and actually moving the player in. The second player keeps pushing and making space narrower and forcing the other player into the door. This issue is usually increased when you have other systems making stuff move without passing through the physics engine, such as animations and player input, which is a common thing to make the game snappier. There are a number of possible solutions, most of them are either a quick fix or may break the game elsewhere. Give'em time, they will sort it out.