Vista - Why is there multiple folders for Sent, Deleted, etc, for IMAP accounts?

I noticed there are the following folders that are replicated unnecessarily:
Sent & Sent Items
Deleted Items & Trash
I can't delete Sent Items and Deleted Items. So why do some items end up in Sent Items and other in
Sent? Would the Sent Items be the ones sent from WLM and the Sent the ones sent from Webmail?

"Rick Z" <oooo.ooo.com> wrote in message
news:Ov3DQj4FKHA.4316@xxxxxxWLMail has no way of knowing which folder is which on your IMAP
server - the folder where deleted items go might be called Trash or
Bin or Rusl or Slettet, so you have to tell it. Right-click on the
account name in the Folder pane and select Properties. On the IMAP
tab, put the names of the special folders on the boxes and tick the
box to 'Store special folders on IMAP server'.

WLMail's own special folders (Sent items etc.) can't be deleted.
--
Noel