Cats have two goals in life. Or at least mine do.
Out one door------and in the other.
It seems that there is always a cat wanting out the back door. It then walks around to the front door and asks to come in.
Or there is a cat at the front door wanting out, and it promply walks around the house and asks to come in the back door.
Out of the twenty some cats I have had they have all done this.
Or maybe it is a goal to annoy their masters (slaves).