An old style that's still in practice to this day , probably some hard learned Skandic idea(often the best) is to sharpen one side finer for chopping notches frozen moose/caribou and have the other side sharpened at a steeper angle for the splitting of birch and spruce when it's -40 and you just got unstuck from the overflow on a crossing you know you should'nt have done before the dang Sno-go sank.
One side is sharper for loping off limbs, and the other for cutting bigger diameter wood without getting stuck. also useful for felling, first hit with the blunter edge, second hit to cut out the chunk. then repeat.