Thanks for your reply, Jane. However, something must still be awry in the database, because the duplicates still appear on the author page for Yotam Ottolenghi, one on 84 shelves and the other on 31. The chain symbol on the UK edition shows that the 84-shelf version (pub date 3/9/2011) is linked. And, when you click on the 31-bookshelf listing (pub date 3/23/2011), it goes to the 'not found' page, probably because it has been deleted. So it may have been merged, but it still appears, at least in that setting. And there is no error message if you click to add it to your bookshelf, though it would probably not appear when you went to look at your bookshelf.
Another (related?) anomaly is that if you enter 'Ottolenghi' in the Library/Books search box, only two listings appear: the book _Ottolenghi_ and the UK edition of Plenty; the US editions are missing altogether.