There's been quite a few reports of people getting duplicate SMSes in the ViperDNA ROM thread. I think I have, unfortunately, found the cause. The other day, I got a SMS from someone not on my contact list/nor anyone I recognized at all. It was like spam email, but from SMS with a link to some site to boot. I brushed it off and just deleted the message. I was reading Android Police's new article on Android anti-virus apps. I was surprised to see my $15 Kaspersky app doing so poorly, so I uninstalled it and installed the #1 rated TrustGo. I did a scan and it found a "High Risk" threat in HTCMode. I followed the link provided by the app and, sure enough, Google has acknowledged the vulnerablility.
This vulnerability is being kept very close to Google's chest, so you don't find much about it doing a search for it. It certainly isn't getting a whole lot of press, but it's gotten some.
I tried to delete the app via TrustGo, but it failed. So went into Titanium Backup and froze the app and then was able to uninstall it. I've rebooted a couple times since uninstall and there doesn't seem to be any repercussions from getting rid of it. I highly recommend you do the same.
Just a heads-up. Protect your shiny DNA and your personal info/data,