afaik, its not really possible with OE to do that.   I don't think the
filter that filters based on "where the message is on a specific
newsgroup" really works.

Agent also doesn't do a good job at the filters for crossposts.   What
you ahve to do to get something to work is to 1.  subscribe to the
group that is the problem (like the FA group).  2.  setup a filter
that deletes all the messages in a specific group.   3.  Apply it to
work on all groups.   4.  the offending group has to be ahead of the
others in the download list so that the filter will actually work.

I don't know if that same thing will work with OE.

There is also 3rd party filters like
http://www.netaxs.com/home/v/nfilter/faq.html
that claim to work as a cross post filter and will work with OE.

Sorry I can't be of much more help.   I don't use OE as my primary
reader.  When it comes to the crossposts, generally I just mark the
entire thread to ignore and don't worry about it.