D3 Publisher has an interesting launch bonus for Earth Defense Force 2 Portable. The first print is a "double enlistment pack," which includes two copies of the PSP game. Earth Defense Force 2 Portable has a multiplayer mode, so perhaps D3 is trying to spark a Monster Hunter Freedom trend by promoting cooperative play.
After the initial run you only get one giant bug blasting game for 6,279 yen ($75). Earth Defense Force Portable 2 comes out on April 7 in Japan. As of now, D3 Publisher have not announced the game for North America.