Whenever you see "double something", is never, ever a problem of the scenery, but it's a conflict caused by another scenery. This means, don't waste your time chasing a problem in KLAX by reinstalling it, because the problem is not KLAX. The only case when reinstalling might fix double objects, is if you moved the scenery in the Scenery Library to a lower layer, so the installer will fix this.
Such duplicates might not be so obvious to find, and the FSX Airport scanner doesn't find *all* possible conflicts. A common cause for trouble are those AFCADs supplied with AI traffic packages, like My Traffic, that are made for the default airports, and must be removed if you have an addon airport for the same area.
