Course problems

HOO boy it's been a while since someone posted anything in this one.
Anyways I have a problem and if any of you can find a solution, it would be great.
I was making my game and all that stuff and I decided to make a new level in World 1, so I went to the level manager, made a new level, but when I opened it, it had a previous level in it, for example 1-1. I went back to the real level 1-1 and it's there as well, so I had two 1-1s. I checked the "File" button down right and both of them were "course1" I made a backup of the files and i decided to delete the newest level,but the whole course1 is gone, so the original 1-1 was gone as well, luckily I had that backup. When I created more new levels on the manager it kept putting existing courses in it like course2, course3 etc.
I was able to fix this only by making levels until it finally shows up on a new and blank course,then backup the files and delete the previous levels, but I was wondering if there is an easier way or if there is a reason why it happens.
Also another problem,when I was trying to work on World 6, I made a new level in the manager and it had an existing course, but from World 5. I checked the files and every world had the courses from the previous world along with their own in them. Luckily I only had to delete those files and that's it, but if any of you have an idea why it happens or if there is another way to fix it, that'd be great.
And CONGRATULATIONS for being able to read everything I wrote, I'm bad at explaining.

This didn't happen to me, but I know, how to avoid it. In Save files there are slot directories and in them there are world directories. Find the corect directory and open LevelManagerX (X is 1 for world 1, 2 for 2,...) as .txt file (in any text file editor).
It looks like this:

So copy and paste course1, rename it to course2, open LevelManager1 and Link Area2 to course2 (by changing 1 to 2 in file). Course2 looks now like course1, but in MB you can import template "blank course" (to area2) and start editing without rewriting the level 1.
Hope it helped .

I'm gonna try it next time I get this problem, thanks a lot.