I think it really depends on the school and programs you're in. A BFA in acting at most schools is incompatible with a double major, but you might be able to swing it with a BA. I know at my school, the BA Theatre is 52 units, and I believe a BS Accounting is 68 units. That adds up to 120 units for both majors—before gen eds, which are another 32 (unless you get out of two or three with AP/IB credit). There's also a diversity requirement, which can be fulfilled by a theatre class or another class and three semesters of a foreign language (which you can test out of), which can be up to 16 more units. If you didn't do well enough on the math placement test or your AP/IB math, you'll also have to take MATH 117, which is another four units.
So double-majoring in theatre and accounting at USC can be anywhere from 140 units (if your high school work works out fortuitously enough) to 172 units. USC lets you take up to 18 units per semester at a flat rate (though they don't encourage taking that many, I have every semester, with no problem—but I think that's because of which classes I'm taking). So, theoretically, it is possible to graduate in four years, without even taking summer classes. I don't know if it's possible practically, though, due to scheduling etc.
I'd imagine it would be much easier to do an accounting minor than a double major.