JD is right to suggest that aura is about more than uniqueness. It is about the 'historic testimony' of the object, the traces it bears of where and what it has been.
In his essay, Unpacking my library, Benjamin writes:
Habent sua fata libelli: these words may have been intended as a general statement about books. So books like The Divince Comedy, Spinoza's Ethics, and The Origin of the Species have their fates. A collector, however, interprets this Latin saying differently. For him, not only books but also copies of books have their fates. [collected in Illuminations (ed.So a copy may be testimony to an individual's life: where it was bought, where it has been, what experiences it has been part of, who bound it. It has a provenance and a history, which may be of broad interest. (In FRBR terms, we can say that in these cases the work and the copy equally may have interest.)
Hannah Arendt, trans. Harry Zohn)]
I was recently in The Bata Shoe Museum, in a party of five adults and six children under twelve. The museum kept everybody's attention - well, for a while anyway ;-) It is really very well done. Shaq O'Neal's large basketball shoe in particular generated interest among the children: not only its size, but the fact that it had been part of an unrepeatable experience, fascinated.
Benjamin goes on to say:
The phenomenon of collecting loses its meaning as it loses its personal owner. Even though public collections may be less objectionable socially and more useful academically than private collections, the objects get their due only in the latter.This seems strange, and is countered by our experience in the Bata Shoe Museum, and by Fintan O'Toole's in the public library. Indeed, many curators will feel about their collections the way that Benjamin felt about his.
O'Toole talked of the fate of library books, of how they create a shared experience:
Books, like their authors, have biographies, they have passed through other hands. The private experience you are having is one that is also shared.Books live in the lives of their readers. Readers also live in the lives of their books. And, in the libraries that he is talking about, I always thought that the mark of very good library staff was that they understood their collections based on the readers in the life of the book, but also understood their readers based on the books in the life of the reader.
So books, and copies of books, have an aura. They bear testimony to their lives and the lives of their users and owners. They may assume significance as part of a collection. They may be annotated or otherwise significantly marked.
However, to come back to my original point. For many books the aura of the copy is low and the ability to transmit the content in new forms may be welcome. That does not mean, of course, that for some books, the user will be drawn back to the artifact, even when it itself is a mechanical reproduction.