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