My dad and another photographer took the same picture of the same bird, a crane, at the same time and the same spot. Ibsaw both of them, and they are exacly the same. Both only discovered that after having run into each other again the same day on a different spot. They had quite a few outings together since then.
Fun fact, over a year later my dad and I had almost the same experience at the same spot shooting geese in flight. Judging by the angle, we were maybe just shy of a half a second or so appart. Maybe we should look at EXIF data to be sure!
Seems this stuff happens more often then people think.