The Heir and the Spare — Maya Rodale

All of London is raving about the newly arrived American, Emilia Highhart. She has beauty, charm, wit, and a hint of the exotic. Unfortunately, grace is decidedly not one of her virtues. Staircases, doors, even floors have proven her enemies, often leaving Emilia prostrate and mortified in a pile of muslin. Nevertheless, at her first ball, her dance card soon fills with the names of highly suitable men. But Emilia's eyes are on just one man - the one her aunt points out as the entirely unsuitable Lord Phillip...

In fact, he isn't Lord Phillip. While Phillip, the heir, goes about spending the good family's funds, his identical twin, Devon, the spare, must attend society functions as Lord Phillip - all because of a few blasted minutes' age difference. Soon, both twins are vying for Emilia. And, under the not-so-watchful eye of Lady Palmerston, aunt and chaperon to the young lady, Emilia is unknowingly courted by two different men with the same face! But only one of them is the love of her life...