Apologies if someone has already found this method (it's impossible to check all comments on the forum).
I have just received 34 duplicate emails in my in-box and 830 duplicate spam in my Junk Folder.
I have changed the archive setting to archive folders older than yesterday. This is how.
Open Outlook 2010.
Click File top left corner.
Choose Info which comes up with a list under heading Account Information
Click cleanup Tools under Mailbox cleanup. In the drop down menu box click Archive.
A dialogue box will come up with a window listing your folders. The selection will be on Inbox.
Under the window (still in the Archive dialogue box) will be Archive folders older than:
and there's a small window in which to insert a date.
Insert a date. I inserted yesterday's date.
Click OK to exit.
I've pressed send/receive three times since and received no duplicates. Obviously, to keep duplicates at bay, the date will have to be constantly changed to the day before.
It's not ideal but (if it does work) it should suffice until Talktalk have sorted this out.