VLC Playlist Problems

[cqCHRIS]

I manage a number of playlists, and when creating new playlists using the old one as a start, there seem to be problems.

The new lists have duplication of songs/videos, 4 or 5 duplicate copies of each song in the list.

Also, recently, I have noticed that Playlists which had 20 distinct titles, now have random material added to them. So the playlists are growing to 30 songs....

Why is this happening?