I have attempted to search in the forums with no luck on this. I also reinstalled all fsds software along with the addon managed.
There are countless of forum posts about double scenery. It's normal this wasn't fixed by reinstalling the scenery or the addon manager, because the problem is not caused by anything in our software.
Whenever you see double objects, it's never a problem of the affected scenery, but it's a problem caused by ANOTHER product, namely a conflicting AFCAD. The most common offenders are AFCADs that comes with AI traffic products like My Traffic, etc.
Use the free FSX Airport Scanner program available here:
http://www.downloadcenter.scruffyduck.org.uk/to find AFCAD duplicates at JFK and remove them all.