Harvey Dent is the Gotham City District Attorney. At a young age Harvey was abused by his father and developed a bipolar disorder and schizophrenia.  Harvey eventually rose up out of his darkness and became a beacon of hope in Gotham. During one of the court cases during a trial of Sal Maroni's father, Sal Maroni himself threw acid at dent's face causing half of it to melt off. Dent was immediately sent to the hospital and became insane, Taking up the dual persona named Two-Face.

Two-Face is the alter ego of Harvey Dent. Harvey is charming and brilliant. The voice of Harvey should be different from Two-Face.

Two-Face (the personality) is a mob boss and a criminal mastermind that debates on which side of the coin he goes by.  The voice of Two-Face should sound more coarse and raspy.