I had a rec game once in which the opposing coaches were twin brothers! I had visions of being on the court with my back to the benches and hearing one of them yell something that would solicit a technical, then not knowing which one said it.
BTW - I worked with a partner last year who told me he and his wife had a set of 12 year old twins. I asked him how they told them apart. He said the boy was taller.