Nie podoba mi się to rozwiązanie, ale opłacalne:-
SELECT a.ID,
a.country,
a.region,
a.item
FROM whitelist a
INNER JOIN
(
SELECT group_concat(ID) AS ID, USERNAME, COMPNAME, PUBLISHER, NAME, VERSION, COUNT(*) AS AMOUNT
FROM software_checklist
GROUP BY USERNAME, COMPNAME, PUBLISHER, NAME, VERSION
HAVING AMOUNT > 1
) tmp
ON FIND_IN_SET(a.ID, tmp.ID)