Sure - you can take as many degree programs as you want concurrently. Don't plan on graduating in 4 years but you can take as many as you want. Depending on what else you want to major in and how sharp your advisors are and how much "extra" work (summer, night classes, Maymesters) you're willing to put in you ** might ** be able to do it 4 years (again depending on what your second major is) but it would be very difficult. Even if it means spending an extra year in school I'd recommend getting the second degree as a back up.
My friend is both double majoring in Flight and Economics. He's also partaking a number of research projects through the AT department, on top of working the student advising office correcting people's resumes/cover letters. I honestly don't know where he finds the time. I really think he's a lot more smarter than he lets on. Oh yeah, he's only a sophomore.
Anyhow, it is possible to double major. Like Jason said, it's all about your work ethic. It would be tough to graduate in 4 years, unless you really put the petal to the metal (take >20 credit hours per semester).