[fmw]

A large part of our industry is self-taught. You don't need a specific degree to get a good job - or even a degree at all. Some bigger companies are a bit more formal (e.g. Google, Microsoft) and prefer hiring graduates, but even they look at merit before academic background. There are some jobs that benefit from academic experience, e.g. being a quant on Wall Street, but math or physics is a lot more useful for that than CS. If want to work in a field like that (or want to keep your options open) I'd recommend doing the double major or alternatively just major in math, while polishing your CS skills by working on open source software and maybe a few CS courses.

Getting a job out of college or differentiating yourself shouldn't be the prime motivator for this decision (if considered at all). Whichever way you graduate, you will be fine. It isn't like you're trying to decide between majoring in pottery class at a community college and going to med school. Future employers will be a lot more impressed by the depth of your understanding of your field than how many classes you took and the extra curricular activities are even more important (e.g. open source, internships, personal projects).