Is there any chance to not allow duplicate entries

Hi, I'm using a form to register attendance to an event. However, people forget they had registered and will register again. 

Is there a mechanism I can use on my forms to not allow duplicate entries?

Thank you

You can achieve that by limiting submissions based on IP address (one submission per IP) or browser cookies. Please see this guide. How to Set Unique Submissions on a Form.

Alternatively, you might consider limit submissions based on a form field (e.g. based on email field). How to set Form Limits Based on a Unique Question.

Hope this helps! But, please get back to us if you need further assistance.