What reprise is sung between Dan and Gabe in Act 2, Scene 13? What is symbolized in this song?

Dan and Gabe sing a reprise of "I Am the One," in which Dan wonders how Diana can leave after everything he's done for her, and Gabe reminds him that he is still in his life, no matter how hard Dan tries to deny him. Dan asks Gabe to leave him alone, Gabe insists he's going to remain, and then they both sing of how they were in each other's lives in the moments when they died.