Carlos is a fairly common name, as long as they aren't using the player faction tag, there's nothing you can do about it. Bulldognk once said that as long as they aren't using your exact name, then there's nothing that will be done. He even said 'Bulldog' would be an acceptable name for a player, as long as they leave off the 'nk' at the end.
Bottom line is that Disco is a big universe, and some names will be used by many different people... I made my first character (Drake) before I knew there was another, rather famous Drake on the server. Has never really been a problem for either of us.