can we have a duplicate of a photo book made and printed a few years ago?

Sorry, no. Apple keeps the original only for about a month, just in case there is an issue with the printing quality.

You will have to upload the book again from your iPhoto library.

For future books I suggest you create a separate book library for each book and create the books in them. You can assemble the photos needed for the book in and album in your main library and use the paid version of iPhoto Library Manager to copy the photos to the book album while keeping edits, metadata, etc. intact.

What will crate a library that is usually small enough to burn to a CD or DVD disk for archiving. It can be copied from the disk back to the Mac if you want to order another copy at a later date. This tutorial might help: #9 - Archiving an iPhoto 7(08)/8(09)/9(11) Book for Editing and/or Ordering at a Later Date