Why do I have multiple copies of playlists in my Music library?

As Apple has upgraded iTunes to Music, and as they have progressively forced us to utilize the cloud more and more, my music library has become increasingly messed up.

Let's start with the basic issues first.

At some point my library duplicated all of it's playlists.

I now have at least two, and in several cases, three or more copies of individual playlists. Some of the copies are appended with the number 1. The whole thing has turned into a disorganized mess.

What caused this and how do I correct the issue? I have been reluctant to just start deleting things, because, obviously, I don't want to lose anything.