I just found out that there are two Hercules movies coming out in 2014, I was already aware of the version starring Dwayne TR Johnson but knew nothing about Hercules: The Legend Begins before seeing the teaser trailer today. There is a history of releasing very similar movies in the same year

Prestige - Illusionist (This pair I can forgive since both movies were good)

Armageddon - Deep Impact

Olympus has Fallen - White House Down (I didn't even realize these were different movies at first)

Volcano - Dante's Peak

Mirror Mirror - Snow White & The Huntsman

I'm sure there are a lot I'm missing, I don't understand why a studio wouldn't hang on to a property and wait a few years to release unopposed.

Here is a more comprehensive list of these movies