Depends on the two jobs, the managers, and how far apart the regular shifts usually are.
I worked two jobs for about a year when I was 20, but the first job I usually worked 6AM-12PM, and the second job was usually 5PM-9PM. That wasn't too bad. Working at a kiosk in the mall, you need to be available for prime mall hours, which really limits when your second job can be, outside of a late evening shift, unless you have managers at both jobs who are willing to work around your commitments, which doesn't always happen.