25 pairs of weirdly similar movies that came out at about the same time

Sony, Columbia Pictures / Film District

After the first box-office bomb of the year, Gerard Butler will return to theaters this weekend in the sequel to 2013's "Olympus has Fallen," cleverly called "London has Fallen."

You may remember "Olympus has Fallen" — a movie about a president taken hostage — for bearing a striking resemblance to Channing Tatum's movie "White House Down," which came out three months later.

Critics and fans alike were quick to point out how similar the two movies were to each other.

But this wasn't the first time two films with "twin" plots were released at about the same time, and it certainly won't be the last.

So why does this happen so frequently? It's all about the competition.

Forbes contributor Mark Hughes summed it up best in a 2011 Quora post explaining that sometimes it's just coincidence. But it could also be to piggyback off a competitor's potentially successful — or already successful — project.

Read the rest of his explanation here, and keep scrolling to see 25 "twin" films that have come out months apart in theaters over the years.

1993/1994: "Tombstone" and "Wyatt Earp" are both centered on Western lawman Wyatt Earp.

Box Office
"Wyatt Earp": $25 million
"Tombstone": $56.5 million

Neither film did overwhelmingly great at the box office. "Tombstone," starring Kurt Russell and Val Kilmer, edged out the Warner Bros. film starring Kevin Costner and Dennis Quaid.

1997: "Dante's Peak" and "Volcano" both revolve around the cast outrunning erupting volcanoes.

Box Office
Dante's Peak": $178 million 
"Volcano": $122.8 million

Fox got a little excited with its over-the-top posters for "Volcano." The film did nowhere near as well as Pierce Brosnan's volcano epic in the states; however, the Los Angeles-centered movie picked up overseas.

1998: The Earth was nearly destroyed in both "Armageddon" and "Deep Impact."

Box Office
Armageddon": $553.7 million
"Deep Impact": $349.5 million

Bruce Willis saves the world from an asteroid in the first film, while Robert Duvall tries to stop a massive comet from colliding with the planet in the second.