I get repeat villagers all the time, both in the same game and across different AC games! I actually find this to be more of a blessing than a curse. One exception for me, however, is Bob. I don't like him, and he has been in one of my New Leaf towns, my Wild World town, and he's still in my Gamecube town.
Other than that, I can't really think of anything.
Other than that, I can't really think of anything.