Max Brand 
The Long Chance [EPUB ebook] 

Sam Cross, in payment for a debt, agrees to be Chandler’s body double for a year, fighting his duels, robbing, generally shouldering the scrapes of young bloods in pre-Civil War days in New Orleans. He uses his disguise to rehabilitate Chandler’s name, wins a woman’s love, and tries to escape the penalty of the misdeeds he has undertaken.