If you use a crafter to copy multiple books at once, and have it output into a chiseled bookshelf, all the copies will be placed as a stack in the first available slot of the bookshelf.  Chiseled bookshelves are meant to hold only 1 item per slot, so this can be considered a bug.

To reproduce:

1. place a crafter pointing into a chiseled bookshelf
2. make a written book and put it in the crafter
3. place 2-8 book and quill inside the crafter as well
4. power the crafter
5. notice that only 2 slots of the chiseled bookshelf are full, if you right click the first slot in survival, you will get 8 written books.