Right now we can't tell the difference between them. There are no distinguishing marks. I gave one the name Butu as something of a joke since this was supposed to be Boot 2 (although the new cat was supposed to be another grey striped tabby). We were going to name the other kitten Bix, but we didn't want to have to explain a somewhat racist name. I opted for K-os (chaos) after the Canadian rap artist. The way she explored the bedroom and pounced her sister made the name apropos. Also we kept saying that she was a handful, and there is a song titled "The Stand" by Mother Mother that has the line, "Oh you are a handful" with guest vocalist K-os replying, "I forgot about handfuls."
Now we just have to hope that the other 2 cats and Mesa can get along with the new ladies of the house.