Cycle Travel map doesn't fully match Garmin map

Yesterday I created a route from York to Cockayne in the North York Moors and transferred this to my Garmin Explore. I noticed that the Cycle Travel route didn't 100% overlay the Garmin map - which is not something I have seen before. By this it looked as if there were two roads running in parallel with each other for large parts of the journey. 

I have created lots of  routes previously with Cycle Travel and have never seen this problem before. The only thing that I might have done differently this time was that I didn't pick the Paved option when I selected what I wanted the route to be On. 

Mostly the lack of overlay didn't matter too much but it could be confusuing when you had several roads near to each other. 

I created the route on my laptop with Cycle Travel running in a browser.