It's really not a big deal. I thought I wanted to do engineering, and after my first internship I realized it wasn't for me. I got to try out new things, made a couple of non-CS friends, and only lost a few credit hours (almost everything transferred as "electives").
For freshman year, you're going to be be taking mostly your generic core classes, like sciences, English, and math. Maybe you'll take one or two major related classes.
If you're stuck between majors, try taking the intro class of both majors. They're generally not major restricted like the higher level classes, and you can decide while taking them. Maybe you'll even decide dual majoring is for you. There's also sometimes "certificates", that's a smaller requirement than a minor.
Remember that even Steve Jobs took classes outside of his core major, and those "unimportant" design classes influenced what he built. College is an experience to open you to new ideas, so might as well take advantage of that.
Still, don't stick around too long, since you're paying for those experiences. It'll get mighty expensive if you choose professional student as your major.