Keeping them both and buying Adam will also be a good move provided we don't pay much for adam because we need strength to rotate around players in all areas and covering one area for starters is a good move. I don't count shelvey or spearing as backup strength players because they can't change a game.
I remember a while back thinking that Shelvey really could be our next big star but he has done absolutely nothing when given the chance. Whilst Spearing has shown to be the better of the 2, he is the ultimate Mr Average. I don't think we need to keep them both.