As Simple as A . . B. . Duplex?

This one came from an online auction, and I don't know what to make of it.  The clip is really interesting.  The "AB" logo strongly resembles the "SB" logo found on some Salz Brothers pencils, and the way it is set into the barrel is unique enough that I'm sure there's a patent for it . . .

NOTE:  This article is now included in the print version of The Leadhead's Pencil Blog, available anywhere you buy books, or also from The Legendary Lead Company.

To order, here's the link:  Volume 1 at Legendary Lead Company