The Mainwaring Twins — Alanna Wilson

What can the Earl and Countess of Cumnor do to make their spirited twin daughters, the ladies Lucienne and Eustacia, conform to the rigid rules laid down by Victorian society? Bored by the attentions of a score of suitors fascinated by the rarity of identical beauties confusing the London season, the debutantes vow they will never marry.
But vows can be broken and when Tess loses her heart to a penniless surgeon and Lucy falls in love with the notorious rake Lord Everard Carseldine, their parents face even worse scandal. The girls meanwhile, pursue their loves with a determination that stuns nineteenth century London...