My GF has twins of 16 months, and they always start the day in "the same but different" outfits (ie different in colour, Harry wears blue, Charlie in green) but by an hour later they are mucky so it all goes to whatever after that!

I agree about the telling them apart comments......I am not even related to these boys, but I have neen able to tell the difference between them for ever.......so can only imagine how annoying it is for Mums of twins to hear this!