The Unix time article has concrete example with tables which should clarify the matter. https://en.wikipedia.org/wiki/Unix_time#Leap_seconds https://en.wikipedi

The Unix time article has concrete example with tables which should clarify the matter. https://en.wikipedia.org/wiki/Unix_time#Leap_seconds https://en.wikipedia.org/wiki/Unix_time#Leap_seconds In that example, Unix time goes from 915148799 -> 915148800 -> 915148800 -> 915148801. Note how the timestamp gets repeated during leap second.