Customer's only filling out form once, but receiving multiple auto response emails per day

As the title states, I have 2 customers that are having this problem.  It started late last week without any modifications to the form.  Please help as it's annoying them and throwing my numbers off. 

As we see the submissions, it shows that they are submitted on different dates and times. Since it not happening it might be an issue with the browser. Generally such issues might happen when the browser button is clicked on back that redirects the page to the form. I have tried submitting your JotForm from the webpage and I was able to submit the form once. I also notice that there is only one submission received.

Adding a captcha to your JotForm might help in avoiding duplicate submissions or spam submissions. 

Please see if that resolves the issue and let us know if the issue still persists. We will be happy to look into this issue further.

Forgot to mention it's only happening to Houston artists. I'll try this and hope it works, but i'd really prefer an actual fix rather than an easy work around, but whatever works works. 

I also tried replicating the problem, unfortunately, I wasn't successfully on it. As mentioned by my colleague, this more related to your end user. They might be clicking the back button that resubmits the actual form or they might have a mis-configuration in their browser setup or an extension or plugin that resubmits the page. You could try avoid this by adding a captcha field OR you can also setup your "Form Limits" for unique submissions.

Here's a guide for it: http://www.jotform.com/help/223-How-to-set-Form-Limits-Based-on-a-Unique-Question. If you want one email per submission, you can try checking this guide. 

But I believe the captcha should already work on this one. If you are still encountering this problem, let us know.

Thank you.