Duplicate emails coming in from same email account

I get 2 of almost every email that comes in to my personal email account. almost 3 minutes apart and never consistently..any suggestions?

What type of account is it? Also, do you have filters or rules setup on the account to foward email to your BlackBerry email address, and then at the same time have the accout setup as a BIS account on the device? That would give you two of each email...