The double-sided holders are "modern" film holders, and should work with your Horseman.
The singles are combination film/plate holders, but they're designed for a totally different style of camera, and the film plane won't be in the right place for the horseman (a few mm closer, which will completely throw off your focus).
So you do actually have a stack of plate holders (that will also take film), but they're not for the Horseman or other "standard" backed cameras. They appear to be for German plate style cameras-- I was confused as to why they would have been patented by Kodak in 1933, but looking at the actual patent, the application lists August Nagel of Stuttgart, and Nils Bouveng of Sweden, so I suspect this was an effort to ensure Kodak had control over these style plate holders in the US.
Patent link