Here’s something jaded Manhattanites haven’t seen in a long time: a district attorney who has to recuse himself to avoid potential conflicts of interest.

Manhattan District Attorney Cy Vance has referred two cases away from his office because he and his former law firm were involved in the matters when he was still a defense lawyer, The Post has learned.

Vance has referred the prosecution of the Joseph Stevens & Co. investment firm to state Attorney General Andrew Cuomo, and a low-level construction fraud case to the Bronx District Attorney’s Office.