I have two email addresses set up on my account.
One I use only on an Imac where I have no problem
The other I have on an HP llaptop and every time a send/receive operation is executed it downloads all emails again regardless of whether they have been downloaded previously.
My partner has a seperate talktlak acocunt and has the same problem (all the duplication started after the talktalk hacking event) I have tried changing the settings in my, and my partners, email programmes to delete emails from the server once downloaded but this has no effect.
This has to be a problem on with the talktalk servers I have other email addesses held on other servers downloading to the same email programs where there is no duplication.
Please can this problem be addressed once and for all
Peter