I see Servers in my Serverlist, which are not from my Game

Hello, i see servers in my list, which are not from me / my Game. Has anyone an idea, how i can fix that? I've already changed the port, but it didnt work.

My code, where, my game searchs for open games

 if(GUI.Button (new Rect(0,40,200,40),"Refresh"))
         {
               MasterServer.RequestHostList(gameMode);
         }

Serverstarting

     public void StartServer(string servername, string serverpassword,  int maxusers)
     {
         MatchName = servername;
         MatchPassword = serverpassword;
         MatchMaxUsers = maxusers;
         Network.InitializeServer(MatchMaxUsers,2550,false);
         MasterServer.RegisterHost("DeathMatch",MatchName,"");
         //Network.InitializeSecurity();
     }

Greetings