Using Chomp on 2.1 unrooted, I only get the Chomp notifications. I did so by simply following the steps listed by stranger in post #2.
The only reason I get two notifications now is because I'm using SMS Popup to set different notifications for specific contacts. My girlfriend or best friends have their own, so I know I should get there a bit faster if I hear it, lol. If that's the case, my phone usually pulls in the Chomp notification first, then a few seconds later gives me the user-defined notification via SMS Popup.
Still haven't figured out how to setup different notifications without doing it this way, so if anybody can answer I'd appreciate it (not trying to thread jack).