About two hours, I think. They had to get them back to the morgue before closing time.
While the photo data is useful in one sense (photos taken by the same photographer), it's not useful in another (photos taken by different photographers) because nobody knows how a given photographer had the clock in his camera set.
Still, there's a lot to be learned from those photos, and very little of it goes toward proving the authenticity of the incident portrayed.
I hope you know about the FNC Greg Palkot's tapes from there as well. If not, take a look at this thread from yesterday morning. "Rescue" guys in fresh clothing and sparkling white gloves after supposedly digging through the rubble with their hands. Also, the two "victims" apparently thought they heard "cut" from the director so hopped up from their stretchers alive and well before the cameras were turned off. The props guy did a good job of ripping one guy's shirt half off, but failed to glue on any wounds or squirt on any ketchup. The torn shirt guy was well enough to came back for a second take of stretcher duty in a different location.