WITH SUB_1 AS (
    SELECT
    	EMP_CODE
    	, EMP_LAST_NAME
    	, EMP_FIRST_NAME
    	, REPLACE(EMP_LAST_NAME, ' ','') || REPLACE(EMP_FIRST_NAME, ' ','') AS EMP_NM
    FROM
    	EMP
    WHERE
        VALID_FLG = '1'
)
SELECT
	EMP_CODE         AS CODE
	, EMP_LAST_NAME  AS SURNAME
	, EMP_FIRST_NAME AS NAME
FROM
    SUB_1 a
    LEFT JOIN (
        SELECT
            EMP_NM
        FROM
            SUB_1
        GROUP BY
            EMP_NM
        HAVING
            COUNT(EMP_CODE) > 1
    ) b ON
    a.EMP_NM = b.EMP_NM
WHERE 
    b.EMP_NM IS NOT NULL
ORDER BY
    a.EMP_NM
    , a.EMP_CODE
;