It is likely you are thinking of the film "A Černý Petr" ("Black Peter") which was released in 1987 and directed by Vera Chytilová. The film was a response to a previous film "Amadeus" (1984) which was directed by Miloš Forman.
While there was a rivalry between the two directors, there is no film that explicitly pitted them against each other in a direct, fictional way.
Please clarify your question or provide more context if you are referring to a different film.