Coincidence?

Arthur Butterworth, of Skipton, Yorkshire, was serving the army in an army camp in Taverham near Norwich during the Second World War. He ordered a second hand book on music from a London Bookseller. The book reached him finally. He opened the parcel standing at the window of his army camp. As he opened the parcel a picture post card fell out from the book which most probably might have used as a bookmark by the previous owner. Writing on the side of the postcard showed that it was written in 4 August 1913.But the astonishing thing of this incident is that when he turned the postcard over, the picture showed the exact view that he had from his camp window at that very moment.

Each army camp was given a post code during the second world war to conceal it ,and the posts were not send it in name so sender can never know which camp was it so it cant be thought that someone had done it purposefully. Just a chance? Or what is it?