Congrats on getting accepted to both Duquesne and Pitt--they are both excellent programs!
Here are your two options:
A) Go to Duquesne because your already a student there (and are already comfortable with the school and the professors)
B) Go to Pitt because its has cheaper tuition than Duquense
I would personally stay with Duquesne (don't get me wrong, Pitt is a great school)...but you are already a student there and quiet familiar with Mylan and your professors. It would be sort of disruptive if you left (unless you don't care for Duquesne to begin with). Stick with Duquesne. Congrats again 🙂