SELECT
    EMP_CODE AS CODE
    , EMP_LAST_NAME AS SURNAME
    , EMP_FIRST_NAME AS NAME
FROM
    EMP
    INNER JOIN (
        SELECT
            replace(EMP_LAST_NAME, " ","") AS LN
            , replace(EMP_FIRST_NAME, " ","") AS FN
        FROM
            EMP
        WHERE
            VALID_FLG = '1'
        GROUP BY
            replace(EMP_LAST_NAME, " ","")
            , replace(EMP_FIRST_NAME, " ","")
        HAVING
            COUNT(*) > 1
    ) SN
    ON replace(EMP_LAST_NAME, " ","") = LN
        AND replace(EMP_FIRST_NAME, " ","") = FN
ORDER BY
    LN
    , FN
    , EMP_CODE
;