I've done this with a number of models over the years and it should work just fine... It's also something I've encountered in models I've downloaded from other places. Never had an issue in using them with either DS or Poser if the CR2's are set up properly to call the right parts. It isn't geometry switching... it's just a cr2 that references more than one mesh when loading...

I do have to say though that I use Daz's Figure Set-up rather than Posers for figure creation (I make Poser models but am better with DS' tool set so it's what I choose to use) so I'm not exactly sure how to set it up through Poser's Figure Room... In DS it's drag-n-drop to assign geometries... so if I have a figure that needs more than one I can just assign parts from each geometry as needed but I'm not sure if Poser works the same way. I do know that any figures I've done this with worked just fine in both DS and Poser even when created in DS (I test everything I make in multiple versions of both DS and Poser before releasing them so I do know that multiple geometries in a single Cr2 is perfectly workable)...