create temporary table cnttable as
select
  replace(emp_last_name, ' ', '') || replace(emp_first_name, ' ', '') as fullname,
  count(1) as cnt
from
  emp
where
  valid_flg='1'
group by  replace(emp_last_name, ' ', '') || replace(emp_first_name, ' ', '')
;

select
  e.emp_code as CODE,
  e.emp_last_name as SURNAME,
  e.emp_first_name as NAME
from
  emp e
  inner join cnttable c
  on (replace(e.emp_last_name, ' ', '') || replace(e.emp_first_name, ' ', '')) = c.fullname
where
  e.valid_flg='1' and
  c.cnt > 1
order by replace(c.fullname, ' ', ''), e.emp_code
;