I have 3 pets (my goal is to have a menagerie to be quite honest). I have the kitten, the puppy and the yellow lab. Quite often they follow each other around. It's the funniest thing.

I got the kitten in my first generation and the puppy early in my second generation (and got the lab yesterday). And as soon as I got the puppy, it went straight to following my kitten around everywhere. When I got the lab, it wasn't quite as clingy, not following either of the other two animals right away.