There are, but the non-overlap isn't pertinent to the discussion.There are A LOT of Broncos fans who are not CU fans in the slightest and vice versa
Where they do overlap is the question, as in, "will the success of one detract support from the other?"
I don't think it would, and in fact I think it goes the other way, where success of one actually reinforces support for the other (again, within the overlap).