Le Magnifique (1973) [French/Italian]

a.k.a.: How to Destroy the Reputation of the World's Greatest Secret Agent
(That may not be exactly correct, but it's close. This may have been just a working title.)
a.k.a.: The Magnificent
a.k.a.: The Magnificent One
a.k.a.: Secret Agent

Jacqueline and Jean-Paul Belmondo play dual roles in this spy spoof. He plays a writer cranking out a spy novel, and also portrays the dapper spy in his fantasies. She plays his next door neighbor, Christine, who becomes the femme fatale Tatiana in his novel. The film was written and directed by Philippe de Broca. French actor Jean-Paul Belmondo also had a small role in "Casino Royale".

"Le Magnifique" is available on video; my copy is under the title "The Magnificent", though a few years back it was on video under "Le Magnifique".