Duplicate orders in 1.5.3

My original post that started this has nothing to do with responsive. No responsive at work at all.

Some were having this problem without using a responsive template. I don't have loads of traffic, but now that I do have responsive, I've gotten duplicate orders three times. All three times I've been able to see the customer is using a mobile type service (ie, Verizon & ViaSat). My traffic is now more mobile friendly, so I'm getting sales there now too.
I was hoping other Zen-Cart stores duplicate orders would be reviewed (both static & responsive templates) to see if the customer side is an IP changing issue. For my low volume store, it's not a burden to make a notation on the duplicate and cancel/disregard.
Hope this helps someone that needs a fix.

• jly