Duplicate archive subfolders with Mail.app I have a strange problem with Mail and I cannot understand if it's a bug or not.

When I archive a message, Mail creates duplicated subfolders. They are called "On my Mac" and they are located under "Archive" folder.

All the subfolders, 4 in my case, contain the same message. This is quit strange since if I delete a folder, I cannot find the message anywhere else (i.e. the message is deleted in the other ones).

Here a discussion on Apple forum where it appears to be an unresolved bug:
Duplicate Mail archive folders.

I'm running ML 10.8.4 and Mail 6.5.

Any suggestions?
I've had this problem for quite some time.  I did a completely new install on a brand new machine and still had this problem.  Here was my solution.

Back before Mail had an archiving feature, I had a folder called "Archive" that I used to put mail that matched certain rules.  The presence of this rule caused a folder to be created with that name.  This must have cause some electronic version of confusion.

When I removed the rule and deleted the folder one more time, I was left with a single Archive folder.