WITH EMP2 AS (
    SELECT *
    FROM EMP
    WHERE VALID_FLG = '1'
)
SELECT E1.EMP_CODE CODE,
    E1.EMP_LAST_NAME SURNAME,
    E1.EMP_FIRST_NAME NAME
FROM EMP2 E1
    JOIN EMP2 E2 ON (
        E1.EMP_FIRST_NAME <> E2.EMP_FIRST_NAME
        OR E1.EMP_LAST_NAME <> E2.EMP_LAST_NAME
    )
    AND (
        (
            REPLACE(E1.EMP_FIRST_NAME, " ", "") = E2.EMP_FIRST_NAME
            AND REPLACE(E1.EMP_LAST_NAME, " ", "") = E2.EMP_LAST_NAME
        )
        OR (
            REPLACE(E2.EMP_FIRST_NAME, " ", "") = E1.EMP_FIRST_NAME
            AND REPLACE(E2.EMP_LAST_NAME, " ", "") = E1.EMP_LAST_NAME
        )
    )
ORDER BY REPLACE(E1.EMP_FIRST_NAME, " ", ""),
    REPLACE(E1.EMP_LAST_NAME, " ", ""),
    E1.EMP_CODE;