Locate duplicates with a temp table - duplicates

Question

I am trying to locate all valid/ non expired duplicate ids from a temp table that is created. When I run this script I get 240,000 results. Only about half of the results are duplicates (when transferring them over into excel) What am I missing to get only duplicate results.
I have tried looking in previous questions about duplicates and none of them have worked. The HAVING COUNT (E.ID_NUMBER) > 1 seems to be a common way to do it.
My knowledge is limited in the use of temp tables and not sure if that has something to do with why I am not getting the results need.
I have tried putting the HAVING COUNT(E.ID_NUMBER) > 1 in the 2nd part of the script and only get about 700 results (there should be more than this)
Any help/ suggestions would be greatly appreciated.
IF OBJECT_ID('TempDb..#DUPLICATE_ID') IS NOT NULL DROP TABLE #DUPLICATE_ID ;
CREATE TABLE #DUPLICATE_ID
(ID CHAR(9))
INSERT INTO
#DUPLICATE_ID
SELECT
distinct
E.ID_NUMBER
FROM
EXAMPLEDb..ENROLLEES E
WHERE
E.ID_NUMBER IS NOT NULL
GROUP BY
E.ID_NUMBER
HAVING
COUNT(E.ID_NUMBER) > 1
-----------------------------------------------
SELECT
DI.ID, E.LAST_NAME, E.FIRST_NAME, E.ADDRESS1, E.CITY, E.STATE, E.ZIP
FROM
EXAMPLEDb..ENROLLEES E
LEFT JOIN #DUPLICATE_ID DI ON E.ID_NUMBER = DI.ID
WHERE
DI.ID IS NOT NULL
and is null(e.TERMINATION_DATE,'1/1/2020') > '4/27/2016'
group BY
DI.ID, E.LAST_NAME, E.FIRST_NAME, E.ADDRESS1, E.CITY, E.STATE, E.ZIP