Twins . . . to an almost three-year-old

Anna is sleeping over at our house tonight so her mom and dad can go see a movie (at the drive-in, and Grey is riding shot-gun with them). We've noticed lately that Anna can't quite figure the girls out, speaking of them as "that girl" this or that, even though she used to just guess, and seemed like she got it right more than 50% of the time. Tonight as I was putting her pj's on, the conversation went something like this:

Anna: There are two Catherines at your house.

Me: No, one is Catherine, and the other is Meredith. They look alike, though, don't they?

Anna: Yeah.

Me: They're twins. (way over her head) They look alike, but they're different kids.

Anna: Yeah.

And on to another subject. I don't think she gets it. More twin lessons tomorrow, I guess.