WITH D AS (
SELECT
EMP_CODE,
EMP_LAST_NAME,
EMP_FIRST_NAME,
REPLACE(EMP_LAST_NAME, " ", "") || REPLACE(EMP_FIRST_NAME, " ", "") Z
FROM EMP
WHERE VALID_FLG = '1'
), D2 AS (
SELECT
    *,
    COUNT(*) OVER (PARTITION BY Z) AS ZZ
FROM D
)

SELECT
EMP_CODE  CODE,
EMP_LAST_NAME  SURNAME,
EMP_FIRST_NAME  NAME
FROM D2
WHERE ZZ >= 2
ORDER BY
Z,
EMP_CODE