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 doesn't 100% overlay the Garmin map - which is not something I have seen before. By this I mean that 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. 

Mostly the lack of overlay didn't matter too much but it can be confusuing when you had several roads near to each other, particularly if you are trying to navigate through a town.  

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