Quote Originally Posted by Mirage View Post
They say game developers want more space, use dual-layer discs. SO3 came on two single-layer DVDs after all, not two dual layer DVDs (though that's because two single layer discs are cheaper than one dual layer).
A dual layer disk has slightly less storage space than two DVDs.

Could have been that the game could be stored on two single layer disks, but not a dual layer one.