Vad sägs om:
SELECT [Acd_unq_id] = MIN([Acd_unq_id])
, [Emp_unq_id]
, [Acd_BImg1] = MAX([Acd_BImg1])
, [Acd_BImg2] = MAX([Acd_BImg2])
, [Acd_RImg1] = MAX([Acd_RImg1])
, [Acd_RImp2] = MAX([Acd_RImp2])
, [Acd_RImg3] = MAX([Acd_RImg3])
, [Acd_Active] = MAX([Acd_Active])
FROM ADVERT_CAMPAIGN_HEADERS
GROUP BY [Emp_unq_id]