Those are the same voice actors as the Nintendo 3DS, which is hardly surprising: Level - 5 wasn't going to redub the whole game just for the fun of it. (perfectly-nintendo.com)
And if you're looking for more looks behind the games, check out six true tales of gaming history and characters you never knew had the same voice actor. (gamesradar.com)
It could also have nothing to do with Metal Gear at all, Kojima could be using the same voice actors for different characters in (for example) Project Ogre. (metalgearinformer.com)