Looks about right for a dually, I struggle with the nose band as well on my cob. Have her in the black one and it tends to be quite low down on her but the smaller one wouldn't fit her.
Noseband needs to be tighter or it will not work properly. Tighten it underneath too. The collar should not be moving about or slide to the left or right. It's a control collar and shouldn't be used sloppily as you would with something you'd just chuck on to bring in from the field.
Yes agreed - it look fine and need to fit snugly to be effective. The nosebands tend to come up quite high so as not to interfere with the rope nosepiece.
Don't forget that you must not tie up on the rope rings in case they pull back - there is a normal ring under the chin for this, although I am sure you are already aware of this x
I would personally drop it a hole and tighten around the nose. Did you get the DVD with it telling you how to fit it? I use the black one on my cob they are very effective if you do the groundwork properly. Good luck with it. You can watch some of the instructional videos on YouTube.