And why are there so many? Seems like one would do but there are three and sometimes four as if something is being duplicated?
BaseCamp routes based on location of the Waypoints. If a Waypoint doesn't fall on a road, BaseCamp will find the nearest road for routing, fly out to the waypoint and return. All you need do is make slight adjustments to the Waypoints (Move Tool) such that they are on the proper lane/side and in order for the direction of travel in the route.
Looking to this thread as well as to your other thread I get the feeling, that something is corrupt in your system. A possible place is the cache of basecamp ( in the folder c:\user\username\Appdata\Local\Garmin\Basecamp) so I propose, you should stop basecamp, delete the complete folder and restart basecamp. (or instead of deleting the folder , rename it so if something unforseen happens, you can reestablish this folder.) If Basecamp does not find this folder, it reestablishes it itself and reads the data once more in. I had once also map problems, which disappeared after deleting this folder.
That is troubling. I have not seen that before but it would appear as though if the route is traversing the same segment that this may happen I suppose. I would be interested in seeing the route. The arrows are drawn at intervals along the total distance of the route, but the current segment of the route is not known at the time we draw the arrows. To us the route lines are just that... Lines on a screen. Would it be possible for you to send me your rout via the BaseCamp help email? You can export it as a GPX file. We won't share your private information.