Mat -
You should remove one. Kill her and leave the body behind. Pretty sad. Or just take her two miles away and set her free.
You can do this as you have described, but the risk is higher that you may result in injured queen remaining or two dead queens. This is an OK method when one of the queens is atleast two years older that the one you want to succeed, because the younger queen will have a stronger pheramone.
If you can, but your most vibrant, healthiest queen on top (Or above the newspapers) the newspapers should be sliced with a razor blade to allow the scents to mingle.