Because one was injured while running away from his new home back to his old home miles away and when no one was there he naturally came across the street to visit the neighbors. And because the other one can not stop biting and scratching herself raw.
I give you cones of shame.
This one is super pissed regardless of the fact that the royal blue makes his eyes pop.
And this one imagines if she sits by your side, wagging her tail and smiling at you adoringly you will take this cone off because green is definitely not her color.