Also,  if you want to get back the PERSON records instead of the SOC_SEC_NO try…

WITH CTE

AS (SELECT SOC_SEC_NO

    FROM PERSON

    GROUP BY SOC_SEC_NO

    HAVING COUNT(*) > 1)

SELECT PERSON.*

FROM PERSON

INNER JOIN CTE ON (CTE.SOC_SEC_NO = PERSON.SOC_SEC_NO)   

Hope this is useful,

Edward