select EMP_CODE as CODE, EMP_LAST_NAME as SURNAME, EMP_FIRST_NAME as NAME 
from
(select EMP_CODE, replace(EMP_LAST_NAME, " ", "") as EMP_LAST_NAME
, replace(EMP_FIRST_NAME, " ", "") as EMP_FIRST_NAME, VALID_FLG from EMP)
where VALID_FLG = '1'
group by EMP_LAST_NAME,  EMP_FIRST_NAME
having count(EMP_LAST_NAME) >= 2 and count(EMP_FIRST_NAME) >= 2
order by SURNAME, NAME, CODE;