Seems there had been some machine misfunction (more likely user error).  

She was queuing up for the other machine with this photo in her hand.

I waited to see how events would unfold.  In rage she ripped up the photo and threw it in to the original photo-booth.

A few moments later she picked the bits up and stuffed them in to an old sandwich bag in the corner of the booth (obviously throwing the photos away).

I waited until she went in to the other booth and quickly went in to the original booth, grabbed the photos and walked briskly to my train (without looking back).

This picture collection thing is becoming an obsession ...