WITH tmp AS(
    SELECT
        REPLACE(EMP_LAST_NAME || EMP_FIRST_NAME, ' ','') AS FULLNAME
    FROM
        EMP
    WHERE
        VALID_FLG = '1'
    GROUP BY
        FULLNAME
    HAVING
        COUNT(*) >= 2
)

SELECT
    EMP_CODE
    ,EMP_LAST_NAME AS SURNAME
    ,EMP_FIRST_NAME AS NAME
FROM
    EMP
WHERE
    VALID_FLG = '1'
    AND REPLACE(EMP_LAST_NAME || EMP_FIRST_NAME, ' ','') IN (SELECT * FROM tmp)
GROUP BY
    SURNAME,NAME
ORDER BY
    REPLACE(EMP_LAST_NAME || EMP_FIRST_NAME, ' ','') ASC
    , EMP_CODE DESC
;