This surface bug apperas on all importetet models. And it's no dubble imported model. In common way I use .3ds format. I can send you project file for discaver the issue reson. This bag allwayes apperas on the all imoprted models. And also, today I founded the simelar flikering but in this time on reflection plane. It's build in object, stage deck and native material. I tride to adjust the reflrction plane, but it only affected on a position of artifactes.