Can I cook two types of dried beans simultaneously?
Most beans can be soaked and cooked together with two exceptions.

The beans should obviously have similar cooking times. For example I wouldn't cook chickpeas with other, harder beans because the chickpeas would be mush. Most varieties do have similar cooking times so this isn't often a problem.

Second, black beans shouldn't be soaked with any other beans because they will stain the other beans a very unappealing gray color. Admittedly this is cosmetic but I soak my black beans separately