That DUB double bag is not a good thing. Besides the bag weighing a bunch, the design is kind of funky. It only has a single zipper, and you have to lay the bag flat and take the top bass out to get to the bottom bass. Not good, although the alpine strap system that is so cumbersome and overdesigned on the new Slim Bag is actually very good and a positive on the double bag, due to the huge weight of that bag combined with two basses.
The best double bag I've experienced is the double bag used by Fodera. Fantastic combination of light weight, thick padding (not as much protection as the in-Case or Sadowsky Porta bag, but much more than a typical bag like the Mooradian), and it has double zippered, separate compartments for each bass. Very nice.
I can't remember who the OEM is for that bag, but it's a good one. I think TBer Wilbyman knows. GREAT double bag.
Edit: I like the original In-Case Slim Bag so much that I found a new one in the box that was left over inventory from before they changed the design, and have it stashed away in case the one I use ever wears out! The new one is a quality bag also, but the change in design made it less preferred for me versus the Sadowsky Portabag, which is pretty close in design to the original Slim Bag. All nice stuff.