No, it isn't. Normal creatures that drop raid-only items have a unique system for these loots. They The items are added to the creature's loot along with the special raid spawn. Using, Using Loot Prey, Loot Potion or during Double Loot event, you'll only get a second roll of the creature's common loot. This also applies to Amazon Set items during the Femur Hills raid, for example.
By the way, I don't know if you created the image to illustrate the question or got it from somewhere else. If it's the latter, I hope you noticed that "screenshot" is a very poorly made fake and not a real double drop of the backpack.