Have a look at the second link in my signature - down the end are three interesting facts, and the second is that four U2 songs have opened and closed the same concert - The Ocean (10 times), 11 O'clock Tick Tock (7), Vertigo (2), and Elevation (1). Judging by the ATYCLB promo tour, it seems not uncommon for U2 to repeat some songs at promo concerts, and this definitely seems to hark back to the early days of the band when songs would be played multiple times in concert (the most common songs to be repeated were The Ocean, 11 O'clock Tick Tock, and I Will Follow).