Our understanding at this point is that dual degree students, especially in voice, would spend the first two years exclusively in their music program. Yet, especially for voice, their four language classes do give them a big overlap for non-tech second degree/major (e.g. Psych). Or, satisfy four classes for general ed requirements, depending on the school.
Also, unlike other instruments, one just can’t sing all day long, which means fewer ensembles and chamber groups.
But again, we haven’t been there yet.