I know someone that did it. She didn’t tell the manager at the corporate store though so

Sometimes depends on the licensed location. I have a coworker who works corporate and at a Tarbux, she's not a full time Tarbux barista, she just works at Target. It's just that sometimes Target has people who are both baristas and cashiers etc. So no one cares.

You're not supposed to unless you're given permission.

You are allowed to work at both as long as you’re not a supervisor at either of them!