Weird Player Glitch

Basically I see a bunch of players on the corner of my map, I go check it out... @Krabzz is one of the players in the corner of the map, I teleport to him but he's not actually on my map. I don't know how instances of the players got onto my map and stayed there but these players are 'fakes' and I don't really have any guesses on the cause of this glitch. Plus those players aren't adding to the player count on the Scoreboard.