In an unusual agreemnent between Universal Pictures and Steven Spielberg's Amblin Entertainment two sequels of "Back to the Future" will be made one after the other this year.

Production was scheduled to start yesterday for the first, which will star Michael J. Fox under the direction of Robert Zemeckis. They teamed for the original sci-fi comedy, which grossed $200 million domestically. The first sequel will be released for the 1989 holiday season. The second, also with Fox and Zemeckis is scheduled for summer 1990.