We're getting multiple submissions from the same users

We have a form on our site. We have been using this form for over a year now without issue. However, recently we started getting multiple submissions from the same users usually within 1 - 3 minutes of one another.

The business stakeholder is not happy about it and I can't explain it. We put language on the form telling users to only click the submit button once, but it's still happening.

We never had this issue before.

I exported a spreadsheet of all of the submissions we received to date and highlighted some of the duplicates for your reference, but this form will not allow me to attach it to this post.

This usually occurs when the user is on mobile and their browser caches form data.  In some browsers, pressing back on the browser reloads the submit page instead of the form.  If the form data was cached, it would be forwarded as if the form was submitted.  Adding a captcha to the form generally prevents this from happening:

https://www.jotform.com/help/205-How-to-Add-a-Captcha-Field

Okay, thanks. I've added a unique submissions filter using the submitter's email address. Hopefully, that will solve for this.

The Unique Question feature will prevent duplicate submission. If it happens again while the The Unique Question feature is enabled, please let us know. 

Will do. Thanks.