Be sure to add a couple hundred dollars for some very good bookbinder to restore them. After all this time, their bindings seem to be disintegrating pretty badly. No, scotch tape will not fix that!

Unlike today, all the early Scott Internationals up to about 1940, were sewn-bound, not loose-leaf, so as more stamps were issued, Scott just issued another volume, four volumes by the 1930s. Most had cardboard covers with paper coverings (colored brown, hence they're called he "Browns"). So these two leather-bound volumes are a bit "upscale".
Hardbound albums continued up to about 1940 or so when the Scott Specialty series of individual regional and country albums was born -- using the same page layouts as these albums. At that time, a "new" briefer "International" was born, the one we still have today. It was about then that Scott began making loose-leaf albums, allowing collectors to add new page supplements over time and move pages around as they liked.
There were even earlier volumes of the Scott International going back to about the 1880s or so -- when there were not a whole lot of stamps! For a long time, these albums were one-volume only and what sold was mainly the cardboard and paper-covered variety.
So this looks like a fairly rare leather-bound set, no doubt designed for collectors with money. After more than a century, the leather covers and leather 'hinges' are failing. I imagine few of these were ever sold which makes them kind of interesting and rare. But their pages will be identical to other versions of the album. Nicer covers did not mean a different album, just a fancier one.