This has nothing to do with LRG. Jeff Smith, head of Special Reserve Games, is holding back the artwork for both versions until after the preorder ends. He stated that the artwork shown so far is just placeholder art, so both covers have yet to be revealed. He wants people to buy The Messenger for the game, not the art. He mentioned this on Discord.
Then why have different artwork for each distributor? Why even have artwork at all? Either this guy has failed upward with limited intelligence to get to this point in his life or he's clearly lying, as in someone effed up and he's covering for it.