[Logic_]

PHP код:

                format(string,sizeof(string),"*** Player %s has been banned by Administrator %s.",playername,adminname);
                SendClientMessageToAll(red,string);
                format(string,sizeof(string),"[Reason: %s]",params[2]);
                SendClientMessageToAll(red,string);
                SaveToFile("BanLog",string);
                print(string); 


You are using the same string variables, thats the reason.