I get annoyed when I get caught buying a book I already have because the publishers have re-issued it under a different title. I just bought 2nd-hand "the Real Flavour of Tuscany" by Lori de Mori, and it appears to be a reissue of her "Bean Eaters and Bread Soup". Maybe one of the children can use it.
I feel this is sharp practice, and seems to be becoming more common.
Giving the same book different titles for the US and UK markets is another variant.
Who said "Barabbas was a publisher...."?