All This For Love - Denise Robins - Google Books

https://books.google.de/books?id=MuE3AgAAQBAJ

Though cousins Sally Browning and Philippa Frome are identical - in looks but not in character. When the married spoilt Philippa persuades her twin to pretend to be Mrs Frome so Philippa can run off on holiday with her secret lover Sally can only…