Yes, each title added to Bookvault should be unique.
If you want to have different versions of your book, then these would need to be setup as new titles. So if you wanted to offer a paperback and hardback version of your book, as well as a b&w copy or full colour copy, you would need to add 4 separate titles to Bookvault.
If you had a title already added to the system, but then wanted to change that or experiment with a different finish - then you would be able to edit the existing title on Bookvault and make those changes.