Is there a way to delete duplications?

If I don't delete the duplicated names, I will reach a false capacity! Thanks,

You can use this app to delete duplicate submissions from the user.

http://duplicate-delete.jotform.io/

You can also prevent duplicate submissions when you enable unique submission option in your form settings.

Guide: http://www.jotform.com/help/64-What-does-Unique-Submission-Mean?