How do I block Duplicate Entries based on a particular field in Google Forms

Question

How do I block Duplicate Entries based on a particular field in Google Forms (For Eg: I am Collecting Contact Details and I don't Want duplicate entries based on Mobile Numbers)

Answer 1

There is currently no option or built-in feature that checks and prevents duplicate field entries for Google Forms.

As a workaround, although it won't prevent the user to submit a identical value, you could do some validations using Google Apps Script and delete duplicates from there. Also, see this post.