Mother of all double runs.

The other week I was shelf-reading at my library job up in a folios section, and I discovered the mother of all double runs:

An entire section (like a book shelf) with one run of numbers, and then another like third of a book shelf afterwards that began where the entire section did and went through the same run of numbers, before merging into the numbers that came afterwards and everything was normal again.

I had no idea how to even deal with something that large, so I tilted some books down on their spines to mark it, and then when I finished shelf-reading I brought the issue to the attention of one of my supervisors.

He didn't seem all that concerned that there might be some books declared lost in there - someone could have easily sought a book in one part of the double run and not the other and then went and declared it lost! - and so he said to report it the next time that I worked, and more than likely I'd be the one sent to fix it, where I'd go up with a cart and merge the books.