I get duplicate submissions submitted at the same time, how to stop them?

i have in 5 min 200+ contact request from the same user

Hello,

Thank you for contacting us.

I have checked your form and submissions. It might be possible that the users of your form submitted your form multiple times or it can also be a spam. I am thinking that the duplicate submissions are being caused by spam.

You can take advantage of our unique submission feature to block multiple submissions from one system of one IP address by setting the "Loose check" or "Strict Check" respectively.

Here is a guide to help you set unique submission in your form: http://www.jotform.com/help/64-How-to-Set-Unique-Submissions-on-a-Form

You can also use our unique question feature to prevent from submitting duplicate submissions. Example: You can set one of your forms questions (like cell number or email address) to be a unique question. This will not allow a user to use the same cell number or email address to submit your form.

Here is a guide to help you: http://www.jotform.com/help/223-How-to-set-Form-Limits-Based-on-a-Unique-Question 

I hope it helps. If you have any questions or issue, please do not hesitate to contact us.