The Internets is Smart...

... and it looks as if it's not a terrible thing, just a lack of ventilation and/or room, as I suspected when I saw the top bars were completely lined with bees. So adding the super and going in to look around and make sure it's full up will be enough to deal with the rest of it.

I may also move the doubled-up frame closer to the edge of the bottom box and see if there's a way to get it out of circulation completely.