If you're referring to this Sim(AFS2) there are not so much doubled sceneries available except
that maybe some community-members made area's are conflicting with some payware regio's.
Most known is LOWI from Orbx in conflict with local Austria made scenery of same area.
If you give a detailled overview where you remark the flickering objects then it's easier to findout
where you have to look in your folder- & file-structure.