I’m talking only of movies with different directors/casts/studios and not back-to-back sequels.
Chistopher Columbus: the Discovery and 1492: Conquest of Paradise were both big budget films designed to cash in on the 500th anniversary of Columbus’s voyage. The first had the odd casting of Tom Selleck as a Spanish king (with a bloated Brando as Marlon Brando in a monk’s robe) while the second starred Depardieu. Both flopped.
A Bug’s Life, an animated flick about a regular worker ant who becomes a great hero and marries the princess, came out in Summer 1998, as did Antz, an animated flick about a regular worker ant who becomes a great hero and marries the princess. (Antz was better, at least imo.)
Deep Impact, a big budget summer release about astronauts and folks on Earth trying to stop the destruction of civilization by a comet, came out just before Armageddon, a big budget summer release about astronauts and folks on Earth trying to stop the destruction of civilization by an asteroid. (I think the latter made more money but the former was way better.)
Currently there are two multimillion dollar films in production about Capote’s research and writing of In Cold Blood. One stars Philip Seymour Hoffman as Capote while the other one stars Dobby the House Elf as Capote and Sandra Bullock as Harper Lee.
What are some other examples of jointly timed competing projects?
Wel;l, there’s Rocketship XM, which was rushed into production to compete with Heinlein’s Destination Moon.
I’ve long felt that Sword and the Sorceror, a wonderfully awful sword-and-sorcery movie (what else?) that steals brashly from the works of Robert E. Howard was made to compete with Schwartzeneggar’s Conan the Barbarian, which legitimately took from Howard.
Then there’s Carnosaur, with its dinosaurs created by incompetent DNA, released about the same time as Jurassic Park.
There were those volacano movies a few years ago - one with Tommy Lee Jones (Volcano, maybe?) and one with Pierce Brosnan, the name of which escapes me (and I’m too lazy to look it up right now).
Robin Hood and Robin Hood: Prince of Thieves in May and June of '91. The former went direct to TV instead of theaters so as not to compete with the bigger stars.
and don’t forget Leviathan and the novel “Sphere” (although the movie came much later). It was an undersea monster free-for-all, with only The Abyss being any good.
Even as we post, there are two productions of Beowulf currently filming - one with Gerard Bulter, all around hottie last seen playing The Phantom of the Opera, and one with a script by Neil Gaiman and Roger Avary. The catch - one has the hot actor, and the other has the good scriptwriters but will be animated in the vapid, soul-clenching style of The Polar Express.
I remember being irked because slimeball mini-talent Kevin Costner was slamming the TV series as “boring” and “low budget” when pimping his own abomination.