movie notes : mirror movies

Ever notice how sometimes vaguely similar movies are released within a short time of one another? I suppose the idea is to piggyback on the publicity of the other movie.

Some examples (not an exhaustive list) :
Abyss (1989) vs Leviathan (1989) vs Deepstar Six (1989)
1492 (1992) vs Christopher Columbus : The Discovery (1992)

Volcano (1997) vs Dante's Peak (1997)

Antz (1998) vs A Bug's Life (1998)
Armageddon (1999) vs Deep Impact (1999)
Mission to Mars (2000) vs The Red Planet (2000)
White House Down (2013) vs Olympus Has Fallen (2013)

for your consideration :
Prometheus (2012) vs Small Apartments (2012)

Prometheus vs Small Apartments - So far my list of  similarities includes that they both have a pale, hairless character who is a "big fella" and runs around nearly naked (the skintight underoos of the Engineer in Prometheus and the white underpants of Franklin Franklin played by Matt Lucas in Small Apartments)