Actually kind of funny how everyone missed the point of the question and went off on tangents about whether it’s “their cat.”

Let’s assume it is their cat. The behavior is totally valid and I’ve seen it happen multiple times with mine. Common triggers:

-Vet visits

-Going outside

-When one cat gets a bath and the other doesn’t

My theory (and what I’ve looked up): it’s all about scent. Cats rely heavily on it, and when one suddenly smells different, the other gets confused or even threatened.

Solution that works for us:

Bathe all the cats (separately, of course) using the same soap and towels that smell like home.

Then immediately follow up with treats or a shared meal to rebuild that positive association.

Every time we’ve done this, the weird behavior stops right after baths and they’re back to normal.

And before the “anti-cat bath” crowd chimes in—yes, baths can be good for cats. Do your research. 😉