Anomalous Photo Question

When I was younger I took a school trip to Chester Zoo (in England) with my class.

This was probably the first time I'd ever used a camera -- I was only 7 or 8 years old at the time (1978-79). Suffice it to say that not to many of the others had a camera. I was using an old Brownie Cresta camera.

The very last picture I took was a small group shot of some of the guys in my class. When I was taking the picture one of my friends, Simon made a dash to get into the photo; he would have been caught running in from the left.

I say would have because something odd happened. Before taking the picture I complained because one of the guys, David, was insisting on holding a white plastic bag in front of him. I said he should put it down somewhere because I didn't want it spoiling the photo... yes I complained about that even at that young age! He refused and the others were getting impatient so I took the photo anyway.

Now here's the strange thing...

When the pictures were developed what we found was that Simon was standing in the picture in David's place and David can be seen running into the picture, plastic bag in hand, from the left. We all found very strange and confusing.

Now I realize my memory could have been mistaken but not all of us. Anyway, I don't know if I would call this paranormal, per se, but it certainly is very strange.

Anyone else had this kind of thing happen in their photos?

Thanks for reading

Sounds more like a memory thing than a paranormel thing but noun the less it would be rather odd remembering something one way than it turning out to be something totally different.