Base Camp is loading two routes into my 770 for every one route I import to the 770

Difficult to tell from your description.  What do you see when you view the routes on your device in BaseCamp?  What are these extra routes and how do they link with the other ones?  Here is a case of a picture paints a thousand words so some appropriate screenshots might help.

Here is some pics from Basecamp and my Garmin 770. I'm only downloading the highlighted blue area into the garmin, but I get two entries for the trip. 

Hmmm ... Try the following.  Using explorer go into the GPX folder on your Zumo and delete all the gpx files.  Now boot your Zumo and using the menu delete all the routes.  Check nothing is showing on your device.  Now connect to BaseCamp, check nothing is showing in BaseCamp when you select your Zumo and send the routes again.  Do you still get two routes?

I used explorer to view the GPX files on my 770 and deleted all files on the GPX directory and archive underneath it. I also deleted all files in basecamp. I then downloaded the GPX file from RVTrip Wizard and imported into Basecamp. You can see the tracks that came in the picture below. I then took the last 5 legs of my trip and converted them to routes and loaded them into the 770 from based camp. I took a snap of what the file explorer looks like on the 770 after the download of the routes. As you can see, I'm still getting duplicate entries in my saved routes on the 770. 

I'm stumped then, although how many points do you end up with in the route if you're converting them from tracks? Most garmin devices can only have 30 points, if you have more that may explain why they are split.