You probably have one of this two problems:
1) Your connection to the ISP is weak therefore you receive the same emails
over and over again
or
2) You could have rules that are performing duplicated actions and therefore
having several copies of the same email.
For both you could probably see if the connection to the ISP is good, see
your account settings and take a look to your rules to see if everything is
right...
or,
You can use my software Delete Duplicated Email
(
http://www.rsoutlook.com/us/prods/prod10.html) to delete your duplicated
messages, for only 10usd...