So of course there are the special NPCs who tend to show up at random. Not counting Joan of course. But any given day we may have Redd or Katrina (unless you have her shop) set up in the plaza, Gulliver washed up on shore, and Katie or Sahara wandering around. My question is whether or not you've ever seen more than one of them on a given day. I feel like it's a possibility, but I've never seen it happen.