I have collected RR/Express items for over 30 years, and have watched Wells Fargo items on Ebay for over 10, and in all that time I have NEVER seen an authentic Wells Fargo Guard or Agent breast badge.  I have posted photos of a few of the fakes below.  The first one has a "Tiffany" backmark and just went for over $300 to some unwary bidder (who only had 12 feedback)

A great website for more info is:   www  .  Railroadiana  .  org