select
  t1.emp_code as CODE
  , t1.emp_last_name as SURNAME
  , t1.emp_first_name as NAME
from
  emp t1
  inner join (
  select
    r1.emp_code as emp_code
    , trim(replace(emp_last_name, ' ', '')) || trim(replace(emp_first_name, ' ', '')) as norm_name
  from
    emp r1
  where valid_flg = '1'
  ) t2
  on trim(replace(t1.emp_last_name, ' ', '')) || trim(replace(t1.emp_first_name, ' ', '')) = t2.norm_name and t1.emp_code <> t2.emp_code
where
  valid_flg = '1'
order by
   t2.norm_name asc, t1.emp_code asc
;