select
EMP_CODE as CODE,
EMP_LAST_NAME as SURNAME,
EMP_FIRST_NAME as NAME

from emp m

where valid_flg = '1'
and exists(
    select 1
    from emp s
    where s.valid_flg = '1'
    and s.emp_code != m.emp_code
    and REPLACE(s.EMP_LAST_NAME, ' ', '') = REPLACE(m.EMP_LAST_NAME, ' ', '')
    and REPLACE(s.EMP_FIRST_NAME, ' ', '') = REPLACE(m.EMP_FIRST_NAME, ' ', '')
)

order by REPLACE(EMP_LAST_NAME, ' ', ''), REPLACE(EMP_FIRST_NAME, ' ', ''), emp_code