select t1.emp_code CODE, t1.emp_last_name SURNAME, t1.emp_first_name NAME  from 
(
  select *, replace(emp_last_name, ' ', '') lname, replace(emp_first_name, ' ', '') fname from emp
  where valid_flg = 1
) t1
inner join 

(
  select * from 
  (
    select *, replace(emp_last_name, ' ', '') lname, replace(emp_first_name, ' ', '') fname from emp
    where valid_flg = 1
  )
  group by lname, fname
  having count(*) >= 2
) t2
on t1.lname = t2.lname
and t1.fname = t2.fname

order by t1.lname, t1.fname, t1.emp_code