Duplicate Emails on Blackberry
If your BlackBerry is displaying duplicate emails, you might have your email account set up on both your cell carrier’s BlackBerry Internet Server (BIS) service and your company’s BlackBerry Enterprise Server.
The email that came through BIS probably won’t let you reply, either. You will have to log onto the BIS server and remove your company email account to fix the problem. If you don’t know how to log onto BIS, contact your carrier’s tech support line.