Problem with Mail and gmail IMAP

Hello,

The gmail account is listed on the side bar under 'MAILBOX'> 'inbox'> 'gmail'. This works fine.

Further down the sidebar the account appears again under 'GMAIL'> [Gmail]> then all the sub folders like junk, sent mail etc. This is driving me mad. If I delete anything it reappears. Plus it holds duplicates of the emails in the inbox. If I try to delete the whole account from the sidebar it says 'IMAP command delete failed with server error: Internal folder cannot be deleted'. I haven't deleted the account through preferences because I want the account in Mail.

How do I get the mails to stay deleted? Can I prevent the dupllication of mails in the inbox?

Any help is much appreciated, I miss the satisfaction of a neat inbox!

Thank you.

Rachel