My work tried to get my 8800 hooked into our BES, but I was told "We're running 3.6, and the 8800 won't sync into the system when we hook it up".

So I set my work email up via BIS.

I keep getting duplicate messages.

First, I get a message where it says
"Received Using: Desktop(Secure)"

Then, a few minutes later, I get the same message again
"Received Using: [dgilman email address]"

I'm really new to all this (coming from the Treo 700p), and I'm not having the same problem with my private email.

Thoughts?

Sounds like you're on the BES. Check your service books...if you have "Desktop [CMIME]", you're on it.