We've coined a term in our house:  tabby-morphisis

In our house, we have two tabbies - Pixel and Sneakers. They are best
buddies, and both like to play. Sometimes I will be playing with Pixel
with a string, and I'll head down the hall expecting him to follow.  But
the tabby who catches the string at the end of the hall is...Sneakers.
Once in a while the reverse happens (I was playing with Sneakers and
suddenly it's Pixel attached to the string).

We also have tortie-morphisis, when there is an unnotices change of
Torties (either Cloudy or Misty) on my chest. This usually occurs when
I'm watching television (something engrossing). I'll start out petting
one of them, and notice later that I have the other cat on me!
(Fortunately, I never have both at the same time, as they hate each
other. That would be painful.)

Kalynnda (and Carol and the menagerie of seven)