Might be because they have the dude on steam? Or maybe the dude is playing with someone and they get his steam and join them?
The latest update featured name changing ingame to something different than your steam name. But still some random guys find them in like 5 minutes.
Might be because they have the dude on steam? Or maybe the dude is playing with someone and they get his steam and join them?
It might be because someone on the server dies, it shows the message of the name they search for that see if they are in a game and join them? Or it maybe has a custom GUI/automessager in chat so it says the server name? I dunno ^^