Think about it, given what Bono has said in interviews, plus the name of the tour, and plus the fact that there will be 2 albums out - Songs of Innocence and Songs of Experience. Two different shows for each city makes total sense.
My prediction: the Innocence Show will feature more SOI songs, and more early-material U2.
The Experience Show will feature more SOE songs, and more late-career U2. Each night will be a mix of acoustic and electric. As the tour moves on over time, the setlists will become a little more flexible and playful, and there will be more cross-over.
Well Edge also confirmed the back to back shows will be "quite different" in that radio interview last week. They will hopefully reveal more before the tour begins.
The rumoured follow up and certainly the name of the tour does seem to suggest SOE will be out during a tour. Whether it's released before May or whether they want to leave 2015 to SOI and release SOE in 2016 for the stadium lap is another matter.