Have you tried the two in the same tank? Mine were fine for months and now it's a different story. Throwing my second ngt in my CA cichlid tank today. I think it would add an oddball look to it, lol.....
None that I know of. At least not now. I got the larger at King Aquarium but it was brought in by a customer, the smaller I ordered direct from a wholesaler. Superway had one from a customer but it wasn't there when I went back to pick it up.