Dead Ringer by Lisa Scottoline

Bennie Rosato is fighting the battle of her life -- against her own twin. The action starts innocently enough, with a stolen wallet, but in no time events escalate and the twin wreaks havoc that can be created only by a dead ringer. Her twin tries to destroy Bennie's law firm, Rosato & Associates, and then strikes at her very heart -- which just happens to be otherwise engaged by a handsome, hunky stranger with the perfect amount of chest hair. But when a brutal murder occurs, Bennie realizes that the stakes have turned deadly. And the face of evil looks like her own.