I wasn’t really trying to say anything 
I just misread that sentence because the sentence structure linked “true double degrees” with non-participation in conservatory opportunities so I wanted to make sure that iasetter knew “double degree” meant being in the conservatory and the college. That seems silly now, of course iasetter knows that .
Iasetter, the best thing to do is to really thoroughly check each school that has a conservatory. Many will indeed have better music opportunities for students in the conservatory.
To me, a student who is good at and likes both music and academics can either do a double degree, or can attend a college or university and do music there. This can mean majoring in music (some colleges offer BM’s with more access to academics than others, some colleges have excellent BA programs in music though they are not performance degrees). It can mean majoring in something else entirely but still taking lessons, practicing and performing either in on campus extracurriculars or off campus.
You don’t mention your daughter’s other interests. If she has other strong interests, or even if she is generally academically inclined and wants to explore majors the first year or two, an LAC that does not have a conservatory might be the best way to go. In an area where she can gig.
She could do a music major for her BA (theory, w/ solfege , dictation, music history, ethnomusicology, composition and technology etc.). Or she could major in something else, as I said, and do music on the side.
If she truly wants to be immersed in music, then either a BM program or a double degree would be best.
If it seems like it could go either way, apply to all options. My daughter did this and decided between conservatory and college on April 30 of senior year!!