Changes

ON A.targetname=B.targetname AND A.targetstate=B.targetstate AND A.announceddate=B.announceddate

LEFT JOIN MANoDups AS C ON A.targetname=C.targetname AND A.targetstate=C.targetstate AND A.announceddate=C.announceddate;

SELECT COUNT(*) FROM(SELECT DISTINCT coname, statecode, datefirstinv FROM MACleanNoDups)a;