How to prevent the duplicate submission based on dropdown values?

First, let me please say what an EXCEPTIONAL tool JotForm is and THANK YOU!

Please see this form: https://form.jotform.com/90833729064159

I have a drop down field on the form with a list of names. I am trying to figure out if there is a way to prevent:

1) someone using someone else's name to submit a vote

2) prevent duplicates - two votes on one name

OR, is there a better way to do this than a drop down field?

THANK you!

Thank you for your appreciation!!

We are continuously trying to improve our product and present to our customers all the latest features.

What you could do to prevent the duplicates, enable the unique question feature on the dropdown containing the values.

1. Configure the dropdown to enable unique question:

2. To customize the error message you can do the same from the Form settings:

To get a detailed guide on this functionality please follow this guide:

https://www.jotform.com/help/223-How-to-set-Form-Limits-Based-on-a-Unique-Question

Hope this helps!

Thanks.