Yes true catalin brushes started off whitened because of an instability in the material have slowly mellowed to various butterscotch colors. I think it'd be pretty hard to find 2 exactly the same shade. That's part of the mystique for me .
There's some posts in my Wiki in my Sig that may help you with your restore (though not a lot on boar )
MY WIKI = http://wiki.badgerandblade.com/User:Fidjit | GREAT SOUTHERN LAND = http://tinyurl.com/bbgsl | CONTRIBUTE = http://www.badgerandblade.com/index.php?page=support