I keep both of my Darwins housed together, but then I also haven't had the time or real experience to say whether it'd be a problem or not. They seem to curl up and keep each other company. The bigger one would be quite capable of eating the younger one I'd imagine.
Hell, lets put it in perspective, I'm sure if I was stuck up in a mountain in a plane wreck for a week or so I'd be thinking of donking you on the head and eating you! Give anything a long enough amount of time and just about anything would look tasty hehehehe