I've had to do this before. I had a Massive Attack map as an osz2 and, even though I had the original folder, it'd still break every time I tried to add difficulties. As such, I had to make a new map and transfer the objects. It was a pain.
As this is a new mapper, the reasons could be anything. They might simply want to copy a pattern from another map to see how it works in theirs, or they might have broken something in the map and had to do what I did.