Everything is duplicated

I recreated my database about a month ago, by doing the following:
Under Movies, I created a folder called Other Playlists.
I then moved all of the standard playlists, as supplied by Mezzmo, under that folder.
I did all my own work outside of 'Other Playlists'.

I have come to discover that 90% of my entries in all of the standard playlists show duplicates of every entry.
See attachments for (1) Movies beginning with 'A', and (2) actor is Clint Eastwood.

How might this have occurred and how do I rectify it?
I don't want to recreate the database, and all of the playlists, yet again.

Try this: Right-click on the Movies playlist in the tree in Mezzmo and click Properties. On the Active Playlist Properties dialog, click the OK button to close the dialog. This will kick-off active playlist processing for this playlist and should remove duplicates. You may need to wait 5-10 minutes of you have a lot of movies in this playlist.

If the duplicates remain, then do this: Right click on one of the duplicates and click Properties. On the Properties dialog, scroll down to the bottom and make a note of the file path for the movie. Now do the same for the other duplicate of the same movie. Are they different paths? If they are then you have added two sets of the same files into Mezzmo. If this is the case, let us know and we can help you remove the unnecessary set of files.

Hi Paul, Thanks for your help.
Your first suggestion didn't work, but the second suggestion shows promise.
I've only checked one movie and it appears in different folders.
One of the folders exists whilst the other shows the name that the folder had a few weeks ago, and no longer exists.
I checked that - as I thought - if I right-click to maintain the library the 'Delete non-existent files' - box is ticked.
But I then went to the menu option 'Maintain Library', where the 'Delete non-existent files' - box is not ticked.
I expected them to be the same.
I've set it going but I've got to rush out now (sorry) ...
More news soon.

Update
=====
The duplicates have gone(!), and I feel that I should have found the solution myself. Thank you!
But I'm left with lingering thoughts about the 'Maintain Playlist' panel and the 'Maintain Library' panels.
1. I hadn't realised that they were different - and one has the additional option of subfolders
2. Having discovered that, I can't predict which, if any, fields on either panel, will be sticky - especially when using the Playlist panel against different playlists.
3. I've always been uneasy about using the panel(s) and being confident that I've chosen the options that I want. Choosing the wrong option can cause a great deal of rectification work. I'm probably more uneasy now. This is exacerbated by the risks caused by the 'Maintain Retrieval Settings' sub-panel being hidden.
4. If I discover a series of movies whose attributes are incorrect, is there a simple way of Mezzmo correcting all of those in the same manner but without affecting others? (I can only think of deleting all of the incorrect movies, re-adding them, and running 'Maintain Library' with the 'Only add new items ...' option selected. But I'd still be terrified of doing it, even if I took a backup!).

I appreciate the work involved, but given the authority to specify an upgrade, I'd define this. Each movie to have a 'Metadata Locked' flag. There would be a batch option to set all movies to 'Locked'. Whenever required, the user would be able to unlock individual movies and update them manually or automatically. I'd feel much safer!

Glad you are up and running again.

There is a Maintain Library dialog for maintaining all files in your library. You can access this from the toolbar or the Tools menu. There is also a Maintain Playlist dialog for maintaining a folder or playlist (and sub-playlists). You can access this by right-clicking on the folder or playlist and clicking Maintain Playlist. There is also a Maintain Files dialog for maintaining individual files or groups of files. You can access this by right-clicking on a selected file(s) and clicking Maintain Files.

If you make a mistake and want to correct a file, then simply right-click on the file and click Maintain Files with your preferred settings.

You can lock files from being updated by Maintain Library dialog. Right-click on a file and click Properties, On the Properties dialog, click the Lock icon at the top right of the dialog and click OK. This will lock the file from further updates from maintenance. You can do this to a selection of files as well in one step. Select a group of files (using your mouse, or using Shift+click, or Ctrl+click). Right-click on one of the selected files and click Properties. On the Properties dialog, click the Lock icon at the top right of the dialog and click OK. This change will be applied to all selected files. See wiki post about Properties dialog - http://www.mezzmo.com/wiki/doku.php?id=properties.