Marvel Studios and parent company Disney first declared that they would be releasing a big film on May 6 as they have been releasing first weekend of summer for past decade.
However, Warner Bros announced in January that it would open Batman-Superman on May 6, 2016 as well. The film stars Ben Affleck as Batman and Henry Cavill once again as Superman.
The film was originally slated to release in summer 2015 but the date got pushed by a year.
Marvel Studios president Kevin Feige recently said he had no plans to shift the release date of one of his superhero films on May 6 to avoid a clash.
While Feige declined to give the name of the film, the Hollywood Reporter said it will be 'Captain America 3'.