Don't worry, your favourite DJ isn't about to split themselves in two.
We often find that DJs, bands, and artists play in two different cities and sometimes even countries on the same night.
The organisers simply adjust the set times to accommodate this.
In some cases, it might mean that the act you're going to see is unusually early or late, just keep an eye out for announcements of the running order to ensure you don't miss it.
Please be aware that most music events have supporting artists before the headliner, so this is how some cross over in event timings may occur.