The subject of a discount or premium on royalty payments for "exclusive v. non-exclusive"
licenses has been addressed by Tom Varner has written about this. You will note from
the article the following paragraph:
"Some patent licenses include a royalty reduction provision if the license is converted
from an exclusive basis to a nonexclusive basis.
Among patent licenses that specify a royalty reduction in the event that a licensor
converts an exclusive license to a nonexclusive license
(either by licensing to a third party or by entering the market itself), over two-thirds
specify a royalty reduction of 50 percent."
See Thomas R Varner, 2011.
"An Economic Perspective on Patent Licensing Structure and Provisions,
" Business Economics, Palgrave Macmillan;National Association for Business Economics,
vol. 46(4), pages 229-238, October.
As we travel through the database and read licenses Tom has captured what we also see.
Simple subtraction between exclusive and non-exclusive across licenses is not a very
good measure. Remember that every clause in a license agreement has some economic
value and impacts the royalty payment. So to attribute the difference to only exclusivity
is likely misleading.