select
  e.emp_code as 'CODE',
  e.EMP_LAST_NAME as 'SURNAME',
  e.EMP_FIRST_NAME as 'NAME'
from emp e 
where
  e.valid_flg = '1'
  and (
    select 1 from emp e2
    where e2.emp_code != e.emp_code
      and replace(e2.EMP_LAST_NAME, ' ', '') = replace(e.EMP_LAST_NAME, ' ', '')
      and replace(e2.EMP_FIRST_NAME, ' ', '') = replace(e.EMP_FIRST_NAME, ' ', '')
      and e2.valid_flg = '1'
  ) = 1
order by
  replace(e.EMP_LAST_NAME, ' ', ''),
  e.emp_code