When using BCC or FEC in After Effects you may receive a duplicate filter error (or multiple) upon launch.
"After Effects Warning: there are multiple copies of plug-in effect "name of effect" on your drive."

This is because After Effects has two potential install locations and you have filters installed to both.
Here are the solutions for PC and Mac.
PC-
The two PC locations are:
C:\Program Files*\Adobe\Common\Plug-ins\CS4\MediaCore
and
C:\Program Files*\Adobe\Adobe After Effects CS4\Support Files\Plug-insThe MediaCore folder is accessed by both After Effects and Premiere so remove any duplicates from the 2nd, bolded, path above.*(Program Files x86 on 64 bit OS)
Mac-
The two locations are:
Macintosh HD> Library> Application Support> Adobe> Plug-Ins> Common> CS4> MediaCore.
and
Macintosh HD> Applications> Adobe After Effects CS4> Plug-InsThe MediaCore folder is accessed by both After Effects and Premiere so remove any duplicates from the 2nd, bolded, path above.