Super Duos vs. Twins  plus info on Knockoffs

Source:  https://www.facebook.com/ItsAllJustString/photos/a.992302810784865.1073741870.251291228219364/998801980134948/?type=1

Source:  http://cs.jewelrymakingmagazines.com/bnb/b/beadandbutton/archive/2012/09/18/superduo-two-beads-one-name.aspx
Great Blog Post from Bead and Button