with tmp as (
select
    emp_code as "CODE",
    emp_last_name as "SURNAME",
    emp_first_name as "NAME",
    emp_last_name || emp_first_name,
    valid_flg,
    count(*) over(
        partition by replace(emp_last_name || emp_first_name, ' ', '')
        ) as duplication_count
from emp
where
    valid_flg = '1'
)
select
    CODE,
    SURNAME,
    NAME
from tmp
where duplication_count >= 2 
order by
    replace(SURNAME || NAME, ' ', ''),
    CODE
;