If you double major as an undergrad, when you apply/go to graduate school, do you pursue a masters/phd in both majors or do you pick one? Can you even pursue two masters degrees concurrently? Or will you have to get a masters in one, then reapply to the college later in your life for a masters in the other degree?
Generally you will pick one subject to get a masters degree in. And there are cases when you can get a masters in a field you did not study as an undergraduate (ex. my D was a psych major and is getting a masters in speech pathology). Just be sure you have the prerequisites you need to pursue your field of interest.
Generally, people would do one or the other for specialized graduate study, although some undergraduate doubles relate to graduate specialties. E.g. physics + astronomy to astrophysics, or economics + statistics or math to any graduate study in economics.