Id      Date
305351  1/24/2018
305351  1/23/2018
E5671   10/12/2014
E5671   10/11/2014

----Retrieve days from date difference - Starts
SELECT T1.EMPNO,
         T1.ATT_DATE
FROM (
     SELECT T2.EMPNO, T2.ATT_DATE,
            ROW_NUMBER() OVER(PARTITION BY T2.EMPNO ORDER BY T2.ATT_DATE DESC) as rn
            FROM TableName T2
     )  T1
WHERE T1.rn <= 2
----Retrieve days from date difference - Ends

TO_DATE(T1.ATT_DATE) - TO_DATE(T3.ATT_DATE) "DAYS"

Id      Date      Days
305351  1/24/2018  1
305351  1/23/2018  1
E5671   10/12/2014 1
E5671   10/11/2014 1