Yes, the back twist helps make the two bundles blend into one round string. I pre twist (back twist) the same direction that I twist before making the second loop. This is because after making the second loop twists you fold it back on the bundles and twist two make the second taper. While making this second taper there is no way to straighten the new twists you are adding to the bundles. If you count the added pre twists, and experiment, you will ideally come out with untwisted bundles between the two loops - these will wind around each other making a single round string as you twist the completed string.