Hi there, @jonathan_bruce ...
Nope. When you use the Course Import Tool (using the Guide that you linked to in your question), content is imported from one course to another. If you then change content in one course, that will NOT change the content in the other course. Essentially, both courses can be treated as completely separate.
Now, the only thing that I can think of that would somewhat contradict my above feedback is if you were using Canvas Commons. There's a process using Canvas Commons where you can share a course to Canvas Commons. And then, people can import the course to their own course shells from Canvas Commons. If you make a change in the original course, you can then push that update out to all courses that had imported it from Canvas Commons. (There's a bit more to it than that, but this is essentially the process.) I know you didn't necessarily ask about Canvas Commons, and I'm assuming you're not using Commons in this way, but I thought I'd share.
So, in summary...the two courses you are asking about don't really have any connections once you import (copy) content. They are treated as completely separate courses.
I hope this helps in some way!
