Yes, they did change characters there all the time. We went one time in the early 90's and we had Brer Fox, Brer Bear, White Rabbit, Goofy, Chip and Dale and Pluto. In those days, you NEVER saw Mickey or Minnie anywhere at meals, just shows.
There was a night when it was SO uncrowded that the characters ran out of people to visit and were wandering around. We asked Brer Fox to sit down at our table and spent about 15 minutes "talking" with him by asking questions and he would nod, shake or use some sort of sign language. He "told" us they were required to be out there a certain amount of time, whether or not people were there. He was grateful to be able to spend time with us. We told him to tell his friends that they were welcome to sit at our table with us, which they all did in succession, after they visited with every other table multiple times if they still had time on their "shift".
Our favorite character meal memory EVER.