On the night the clocks go back, the hour between one and two happens twice. In November 2016, at a hospital on Cape Cod, a boy was born at 1:39; his twin came thirty-one minutes later, after the clock had dropped back, and was written down as born at 1:10. On paper the second baby is the elder. Nothing about either of them changed. The night simply handed out the same hour twice, and the birth certificate, which has a space for the time but not for which one, had to pick. This year the hour repeats on the first of November, and somewhere a nurse will look at the wall clock twice.