At the Cannes Film Festival last May, the movie producer Avi Lerner knew he had an alluring property on his hands: Robert De Niro and Al Pacino, who have shared the screen only once before, in 1995's "Heat," were starring in a gritty New York police drama called "Righteous Kill." Studio executives jockeyed to release the film in the United States, Mr. Lerner said, but it was Chris McGurk, the chief executive of an upstart company called Overture Films, who left the Riviera with a deal that rivals said cost him $10 million. David M. Halbfinger reports.