Q: If they undercharged you by error, they can correct the error. Your tuition rates are determined by virtue of your contract with the university; I can't read your contracts or the university's written policies from here, official or otherwise. Perhaps your school has a "student legal aid" clinic that can help you interpret school policies.
A: I asked the school their policy, they do not have one regarding students enrolled in two degree programs. I was enrolled in a lower cost program first before taking on a concurrent second higher-cost program.