I'm not sure I can even explain how much I dislike when people dress their twins alike. We have friends with twins who always dress them alike. If one gets dirty, both get their outfits changed. I know it's their choice, just as it is our choice not to do the "matchy-matchy" outfits.
I have managed to drill this into everyone who might buy clothes for the girls. We often end up with the same outfits in different colors, and I'm okay with that. It's pretty cute and the girls still maintain their own identities. Everyone is happy.
Imagine my shock when the GIRLS decided to start dressing alike. Recently they started creating matching outfits. One day is was blue shirts with their denim skirts. Another day it was peach shirts with their heart leggings. I asked them why they decided to dress alike and they said, "We're twins and twins dress alike."
I nearly fell over. I don't discourage them from dressing alike because it makes them happy. I don't tell them exactly what to wear most days. Usually I just give them some direction like "it's cold, wear long sleeves and pants or you need to wear a dress and leggings." Other than that, it's often a free-for-all. They have gone to school in some truly unique outfits. I figure this is the only time they can get away with wearing these things. If they were ten, people would think they were fashion-challenged. Now people just look at them and smile.
While everything I've read about twins dressing alike reports that the children hated when their parents made them dress alike. For now, our girls seem to love dressing alike because it is their idea. I don't know how long the matching syndrome will last, but they are having fun with it. Me, I just grin and bear it because they are so cute it's hard to dislike them in anything they wear.