This is one of the best Two-Face stories ... and it's less concerned with the number two than you might expect!
Legends of the Dark Knight by Matt Wagner (writer/artist), Willie Schubert (letterer), and Steve Oliff (colorist).
DC, 3 issues (#28-30), cover dated March - May 1992.
Minor SPOILERS ahead, because I kind of have to. [...] http://tinyurl.com/yey62v4