Getting multiple orders placed and charged.

Version: 1.3.7
Payment: Authorize.net AIM

I have looked in the archive and found that it can be an issue with the AIM version. The site is not very busy so I don't think traffic would be a reason for it. It just happened to consecutive orders placed on different days from different people.

I have found some posts referencing EONG and thought about trying that, but for some reason the zip file of it doesn't expand for me. Would switching the payment to Authorize.net SIM stop this from happening? As I said it is not that busy of a site, but it might be picking up soon.