Multiple Mail Folders?

Hi,

I have a series of iMap and Pop email accounts, and for each account there is series of the usual Draft, Sent, Inbox folders, etc., including two sets for the main address which is now an iCloud and .me account. I'd like to clean up the tree structure by dragging all of these folders into one single folder so I don't have to scroll down through them. However, when I try to move several of the folders, I get the following error message:

"The mailbox DELETED MESSAGES could not be moved. The IMAP command “RENAME” (to me/Deleted Messages) failed with server error: Mailbox already exists."

Does this mean I have duplicate folders? If so, is there a way to tell which one to delete?

Thanks-I know the question is a bit vague but hard to explain!