The Justice Department approved the Banc One Corporation's $3.1 billion merger with the First Commerce Corporation of New Orleans today after the banks agreed to sell 25 Louisiana branches with $614 million in deposits. Banc One, based in Columbus, Ohio, agreed to sell First Commerce branches in Calcasieu, Lincoln, Ouachita, and Lafayette parishes to a competitively suitable buyer approved by bank regulators, the department announced. Banc One also agreed that it would not try to prevent other financial institutions from leasing or purchasing any bank branches it might close as a result of the merger.