I have seen a double "suitcase" style which is practically the same as two suitcase stoves glued together. You would of though it would of been cheaper than two separate stoves but in fact it was quite a lot dearer.
The run time on those little canisters would make a double burner and grill a unsuitable product, the can would only last a hour or 2 at best, they only have about 250-300g gas in, the campingaz grill uses 170g/hour on each burned, and 80g/hour on the grill.