SELECT DISTINCT
    e1.EMP_CODE AS CODE,
    e1.EMP_LAST_NAME AS SURNAME,
    e1.EMP_FIRST_NAME AS NAME
FROM
    (SELECT * FROM EMP WHERE VALID_FLG = '1') AS e1
INNER JOIN
    (SELECT * FROM EMP WHERE VALID_FLG = '1') AS e2
ON
    REPLACE(e1.EMP_LAST_NAME || e1.EMP_FIRST_NAME, ' ', '')
        = REPLACE(e2.EMP_LAST_NAME || e2.EMP_FIRST_NAME, ' ', '')
    AND e1.EMP_CODE != e2.EMP_CODE
ORDER BY
    REPLACE(e1.EMP_LAST_NAME || e1.EMP_FIRST_NAME, ' ', ''),
    e1.EMP_CODE
;