I have Volume II and recently bought the 2001 reprint of Volume I, but it turns out the bindings are different. Does anyone know why?

The 2001 Adams reprint was specifically intended to provide a low cost alternative to the original 1982 edition of United States Numismatic Literature. Volume I: Nineteenth Century Auction Catalogues. The reprint was produced by a Michigan firm specializing in good quality low cost production-line book printing and mechanized binding.

The original was printed in two colors throughout on the best acid-free paper available at the time (i.e., expensive at a time when most books were printed on acid stock), and it was bound by hand by Kater-Crafts in Pico Rivera, California.

Typesetting and two-color trapping costs were substantial (remember, computer typesetting and formatting were in their infancy if available at all). Other factors were the substantial cost involved in commissioning twenty-one original drawings for the book and the oversize format.