bialumnal is a good way to describe what you are, but I'm more interested in how you behave sitting in the stands as you watch the 2 teams compete.

Since you have 2 degrees from one U and one from the other, it might be seen as judicious to root for the latter team in the 1st quarter, the former in the 2nd and 3rd, and then make yourself absent for the 4th, leaving the contest to be decided on its own merits without benefit of your unstinting support for either team.