My iphone keeps sending out duplicate sms messages to those I have texted. The duplicate texts don't show up on my phone, but those I have texted are responding letting me know that they keep receiving the texts over and over again. I've already restarted my phone and problem is still active.
I've noted on this forum that a few others have reported this issue as well. I'm not having any problems, but a thought occurred to me... Is it possible that the receiving parties of your messages are seeing this on the lock screen of their iPhones? Because with iOS 5, you can change the number of times that a message will notify you until you acknowledge it. If your phone is on the lock screen, it'll keep alerting you up to a maximum of 10 times every 2 minutes. These alerts will stop once you unlock your phone.
Just figured I'd throw this out there... Of course if they're actually seeing repeats from within the message app itself, then this wouldn't apply.
I have received duplicate texts from others...but everyone I have received them from are not Verizon customers and do not have iPhones. No one has ever mentioned receiving duplicates from me though. The question has to be if the issue is on your end or if it's your phone that's doing it. It could be a network issue and not an iPhone issue. Or, the problem could be network of the people receiving the texts. My issue occurs with AT&T customers...
Ultimately, you might need to contact VZW to see what tech support says.