Graeme,
Well, I have to admit I prefer to call them 'combination process prints' in general, and 'combination gum bichromate and palladium prints' more specifically. This is because there is an unlimited number of combinations that can be made, using various processes, depending on the desired aesthetic.
For example, tri-color gum prints that many people make are often combination gum and cyanotype prints. It is possible, within limits and compatibility constraints, to print many different processes in combination, and gum and palladium is really only one combination from this approach to crafting an image.
---Michael