My grandfather was an identical twin, at least according to all measures but DNA. He looked so much like his brother that no one -- not even their parent or girlfriends -- could tell them apart. They wore necklaces by which people could distinguish them, but In high school, these were broken. Whether that was accidental or deliberate no one learned, but afterward they would often trade girlfriends, without them knowing.
I have very often heard that twins skip a generation. But in this case, it skipped two, because I have two sisters that had twins. One had twin girls, and one twin boys. The girls looked quite a lot alike, but tests proved they were fraternal and not identical. The boys did NOT look alike, and it was and is easy to see which is which. I would love to find records of earlier generations having twins, but this I have not been able to do.
I have found other twins in my research for WikiTree, but I have documented literally thousands of 2-, 3- and 4-cousins of mine, so I don't know how relevant that is.
We also have a remote cousin (3d, I think), with three (yes, 3) twin sisters!