User are placing repeated orders

On some occasions, a user was able to order twice with woocommerce as the pages were not loading fast enough or connection issues or whatever reason I am still trying to understand.
This is not a one-time random error. I simply do not understand how this is happening and how to prevent it from happening.

Here is the reply from woocommerce:
In previous cases where we’ve seen this happening, the cause of the problem was typically a conflict. Issues like this may be caused by either a conflict with your theme or with another plugin. You can read more about plugin and theme conflicts here:
https://docs.woocommerce.com/document/woocommerce-self-service-guide/
The best way to determine if the issue is being caused by a theme and/or plugin is to do the following:
1. Temporarily switch your theme back to the Storefront theme (it’s free)
2. Disable all plugins except for WooCommerce
3. Test to see if the issue has been resolved.
4. If that resolves the issue, then slowly re-enable features until you find the one that’s causing the conflict.
This is best done on a staging site. That’s a copy of your live site, so you can test things out without making changes to your actual site. Some hosting companies offer a staging site service within their hosting plans. If yours does not, there is a great free plugin that will allow you to build a complete staging site with a few button clicks: https://www.ads-software.com/plugins/wp-staging.

PLEASE HELP~~~!

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