Using a jacket on your body and a jacket on your legs isn't multiple use, in my opinion. If it's cold enough for you to be wearing two jackets at once, your legs need insulation too, so you might as well bring down pants. You'd never use the second jacket for anything but legs.
A down vest is multiple use if you wear it on your legs, though. There are times when you'd want a vest and NOT a jacket. You'll use it independently and as part of a sleep system.