SELECT EMP_CODE AS CODE,
       EMP_LAST_NAME AS SURNAME,
       EMP_FIRST_NAME AS NAME
FROM EMP
WHERE VALID_FLG = 1 AND REPLACE(EMP_LAST_NAME,' ','') 
IN
(
    SELECT REPLACE(EMP_LAST_NAME,' ','') 
    FROM EMP 
    WHERE VALID_FLG = 1
    GROUP BY REPLACE(EMP_LAST_NAME,' ','') 
    HAVING COUNT(*) > 1
) 
AND REPLACE(EMP_FIRST_NAME,' ','') 
IN
(
    SELECT REPLACE(EMP_FIRST_NAME,' ','') 
    FROM EMP 
    WHERE VALID_FLG = 1
    GROUP BY REPLACE(EMP_FIRST_NAME,' ','') 
    HAVING COUNT(*) > 1
)
ORDER BY REPLACE(EMP_LAST_NAME,' ',''),
         REPLACE(EMP_FIRST_NAME,' ',''),
         CODE;