Mostly in the Dutch barns where this construction was employed, the so called ankergebint, both wedges and pegs got used, anyway historically. I don't know of an explanation for what seems a redundancy but in the stress testing videos I can say this, orienting the wedge to run parallel with the post doesn't seem as good an idea as a wedge or wedges that are pressing across the grain of the post though I admit to having done it that way myself. Also, and what I have never done, it doesn't seem pine or softwood is so compatible with this choice of joint. The wood used in the ankergebint construction is typically oak of none to high quality, usually from the farmland or local forest.