Re-use Nonce in Repeating Event Signup Buttons

Nonces are not the way to solve your problem. You’re using it correctly. I would look at the $wpdb->insert array you’re probably using, and implement a check for data to exist that matches the proposed “new” entry.

I actually set up a Twilio SMS to fire off when weird validation errors are encountered. I have it text me a message and the database row id. I usually know about the problem while my client is still on their device having trouble. They think I’m magic when I text them and ask if they’re having an issue.