I've heard from some people too that dual majors are frowned upon...if they find out. So depending upon your unit and school they might force you to graduate early if the right person got wind of that.
Like is was told to me by an OC... your degree plan that you do now.. is just to prove that you CAN complete your degree by the age limit. You will never see the degree plan again, and you will probably change it 100 times before you graduate. You can get a degree in anything you want. Technical degree's are "preferred", but arts and science degrees are logical with the time constraints. If you can get a double major without abusing the program(example...spending 2 extra semesters there), then more power to ya.