with T as (select EMP_CODE,
                  REPLACE(EMP_LAST_NAME, ' ', '')  LAST_NAME,
                  REPLACE(EMP_FIRST_NAME, ' ', '') FIRST_NAME
           from EMP
           where VALID_FLG = '1')

select emp.EMP_CODE       as CODE,
       EMP_LAST_NAME  as SURNAME,
       EMP_FIRST_NAME as NAME

from EMP
         inner join

     (select T1.EMP_CODE,
             max(T1.LAST_NAME)  as LAST_NAME,
             max(T1.FIRST_NAME) as FIRST_NAME
      from T as T1
               inner join T as T2 on (T1.LAST_NAME || ' ' || T1.FIRST_NAME) = (T2.LAST_NAME || ' ' || T2.FIRST_NAME) and
                                     T1.EMP_CODE <> T2.EMP_CODE
      group by T1.EMP_CODE) tmp
     on EMP.EMP_CODE = tmp.EMP_CODE
order by (tmp.LAST_NAME || tmp.FIRST_NAME), 1;