WITH emp2 AS (
    SELECT
        EMP_CODE AS 'CODE',
        EMP_LAST_NAME AS 'SURNAME',
        EMP_FIRST_NAME AS 'NAME',
        REPLACE(EMP_LAST_NAME, ' ', '')||REPLACE(EMP_FIRST_NAME, ' ', '') AS trimmed
    FROM
        (
            SELECT
                *
            FROM
                EMP
            WHERE
                VALID_FLG = 1
        )
)

SELECT
    CODE,
    SURNAME,
    NAME
FROM
    emp2 AS 'main'
WHERE EXISTS (
    SELECT
        *
    FROM
        emp2 AS 'sub'
    WHERE
        main.CODE != sub.CODE
    AND
        main.trimmed = sub.trimmed
)
ORDER BY
    trimmed,
    CODE
;