During the first spawn at the start of a multiplayer mission, a few players spawned in with duplicate characters. They were similar to AI players except they had a name tag above their heads when highlighting them with crosshairs and they also did not move. The body of the actual player also had a name tag but no white triangle markers that signify players are in the same squad.
When the non-playing duplicates were shot at, the bodies reacted to the shots but would not die.