imap & fetchflag set "\\Seen", prevent duplicates

[Surendra Singhi]

Hello,
  I am using an imap server, and in my init file I have the fetchflag set to
"\\Seen", so every time when I start gnus, the gnus fetches email from my imap
server and this results in duplicates being created for all the emails. What
should I do to stop gnus from retrieving duplicate emails? Also, I want to have
the seen flag on so that in case if I use the web to access my email and mark
it as read then also I want it to be downloaded.

Is there any way I can force gnus to delete some emails from my web server(such
as junk) but allow the other emails to remain.

Thanks a lot.
I appreciate your helping me.
-- 
Surendra Singhi
www.public.asu.edu/~sksinghi/

"O thou my friend! The prosperity of Crime is like unto the lightning, whose 
traitorous brilliancies embellish the atmosphere but for an instant, in order 
to hurl into death's very depths the luckless one they have dazzled." -- 
Marquis de Sade