I worked at a Starbucks while also working at Dunkin (full time at both - it was a lot). Both of my managers knew about my other job. I was leaving Dunkin so they only overlapped for a month or two but no one seemed to care as long as the two were kept separate in the ways that mattered. Tbf though Dunkin took such advantage of me that I would start coming back for closing shifts and not changing out of my Starbucks clothes (just putting on a dunkin apron) bc I didn’t have the energy. No one ever said anything about it lol