Quote Originally Posted by VDecalS View Post
I think this might be more of a buyer-side mobile device error. I upgraded from 1.3.9h the end of March and started utilizing a responsive template for the first time. I have had two duplicate orders with single payments since then. The first order was on Verizon, where I could see the IP address changed during checkout. The second buyer was using a satellite IP service - the IP started as "172.243.75.61", then switched to "172.243.75.61 - 172.243.75.61".
My site is low volume, so maybe someone with multiple occurrences can prove my theory?
Nice piece of detective work, @VDecalS! I'm sure that the information you supplied will be an aid in determining the solution to this issue.