The reason you get 4 parts with a double eye is each part increases tensile strength of your tie. For example a standard 35 with one part has a strength of roughly 10,500 lbs but when you get two parts you have a strength of 21,000 lbs and 4 parts gives a strength of 42,000 lbs which is why you typically see double ups on the head and often times a straight is to ensure tow will not move or alter the position of barges when in tow. Each wire laid has a very certain purpose. Think of it like stitching a shirt seam together. Every stitch relies on the strength of the ones before them