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