Whats with this? im on ps3 and im playing with people with identical names as each other for example

Tas

Tas(2)

and there always pretty much the same level

You must be on deathmatch and they are all friends with each other. Switch to Mercenary and teams wont be allowed.

no apparently its because you can play splitscreen online

Yea you get an option on the main menu to add a controller and you can have 2 people on the same machine playing.

That's right, it's if you've got 2 people on one machine playing multiplayer..