Twin films

Twin films are films with the same or similar plots produced and released at the same time by two different film studios. The phenomenon can result from two or more production companies investing in similar scripts at the same time, resulting in a race to distribute the films to audiences. Some attribute twin films to industrial espionage, the movement of staff between studios, or that the same screenplays are sent to several film studios before being accepted. Another possible explanation is if the films deal with topical issues, such as volcanic eruptions, reality television, terrorist attacks, or significant anniversaries, resulting in multiple discovery of the concept.

While twin films are often big budget films, a mockbuster can be made with a low budget, with similar titles, aesthetics, or theme as blockbuster films. Mockbusters are usually given more limited release and marketing, intending to take advantage of the public interest in the topic driven by the major film.

Avoiding twin films
Screenwriter Terry Rossio notes that there are always film projects with similar subjects being developed in multiple studios, and that usually only one of them makes it into production in a given period of time, and therefore twin films are better regarded as exceptions to this tendency. For example, the release of the 2015 Whitey Bulger biopic Black Mass led to the abandonment of a planned film about Bulger that would have been produced by Ben Affleck and Matt Damon.

The 2008 film Who Do You Love?, about American record label Chess Records, had its widespread release delayed until 2010 to avoid competing with Cadillac Records, a higher-budget 2008 film on the same subject.

In one case, for the 1974 film The Towering Inferno, the fear of having competing action thrillers, both set in a burning skyscraper, convinced two Hollywood studios to merge their productions into one (all-star) film.

Notable examples
Notable examples of twin films are included in this list:

One story from two perspectives
The term "twin films" has also been used for films produced by the same production company with the purpose of telling the same story from two different points of view:
 * Anatomy of a Marriage: My Days with Françoise (1964) and Anatomy of a Marriage: My Days with Jean-Marc (1964) use the same cast to tell the same story from two different points of view.
 * The World War II films Flags of Our Fathers (2006) and Letters from Iwo Jima (2006) are about the Battle of Iwo Jima, told from the perspective of United States Marines and Japanese soldiers.

Multiple-language films
The term "twin films" has also been used for multiple-language versions of films:
 * Raavan (2010) and Raavanan (2010) use similar casts filming the scenes in both Hindi and Tamil.