Suspect wiring for sconces
I think I've figured out what this is - I imagine there have been sconces here for quite some time (although the ones I removed were more recently updated). I'm guessing these wires were simply extended to the other sconce where there are only two wires - basically this was the older version of what today you would solve with a pigtail. Assuming the new sconces have wire leads I should be able to just couple them in here with a yellow cap.