This question appears in https://controlleddigitallending.org/faq. Specifically for our sponsorship program at this stage, we decided to limit eligible books to those we had no copies of (in the interest of maximizing preservation -- we're as much an archive as we are a library).
In general we're not thrilled about books being destroyed. There's always someone who can benefit from a book. Also, one never knows when a book may have to be scanned again because a digital copy could theoretically become lost, corrupt, or benefit from new tech (e.g. a palimpsest). These are all big reasons our digitization process is explicitly non-destructive.
http://openlibraries.online describes how we are working with other Library partners and including them in our model to help make works more broadly available.
None of this directly answers your question which is probably better answered by a lawyer. I'm just a fake librarian.
In general we're not thrilled about books being destroyed. There's always someone who can benefit from a book. Also, one never knows when a book may have to be scanned again because a digital copy could theoretically become lost, corrupt, or benefit from new tech (e.g. a palimpsest). These are all big reasons our digitization process is explicitly non-destructive.
http://openlibraries.online describes how we are working with other Library partners and including them in our model to help make works more broadly available.
None of this directly answers your question which is probably better answered by a lawyer. I'm just a fake librarian.