For Sisko, I don't know why they didn't just get the guy who played Benny Russell. I liked him. He looked a little like Gabriel Bell.
I think you're confusing them. Gabriel Bell, with hair on his head and smooth face, looked like Avery Brooks. The actor who played Benny Russel, with a goa-dyke and shave head, looked like Avery Brooks. Everyone would know that the coffee was replaced with Folgers!