with
a as (
    select
        EMP_CODE CODE
        ,replace(EMP_LAST_NAME, ' ', '') SURNAME
        ,replace(EMP_FIRST_NAME, ' ', '') NAME
    from EMP
    where VALID_FLG = '1'
)
select distinct
a.CODE
,a.SURNAME
,a.NAME
from a
join a b
    on a.SURNAME = b.SURNAME
    and a.NAME = b.NAME
order by 
a.SURNAME
,a.CODE