Stranger neighbors

With this event I suddenly have several new neighbors I know I did not add myself. They are very active in visiting and their progress seems normal - and they show up in all five of my games.

It is slightly possible these are old neighbors who have suddenly renamed themselves, but I have tried to have a policy of not duplicating neighbors across my Springfields (although not strictly), so I am mystified.

I recall there was at least one thread on the old forum about something like this, but that is all I remember.