A clone which looks like your teammate

[tall tulip]

it would be an entity which could spawn in newer Levels or mybe the office level? It could mimic your teammates movement, it would attack if it gets close enough to you and have also some marks on the back so you can recognize that it is a clone. Maybe similar to the rare content warning clone.

[weary hull]

it's a good idea but not that original, as many horror games already have that

[tall tulip]

yea but for multiplayer it's alwayls fun