Comes two letters

Hello, I installed Chronoforms V5.0.14 on Joomla 3.6.5, php 5.5.38, created a simple feedback form "http://dobrostroika.ru/index.php/otzyvy" everything works, but the mail administrator comes two emails. In the first all the necessary data from the form, in the second only the field names:
name client:
E-mail client:
Phone client:
Message
How to fix this problem? Tried to create a new form with one text field and a submit button, the result is the same. Checked out the standard user registration form of Joomla, comes one letter.

Hi Zarkon,

Something on your website reloads the form submit page, you may add a captcha method to your form and that may fix it, but the real solution is to find what loads the submit page again.

Best regards,
Max

Thank you very much!
Maybe someone will be useful, you need to add to the form field that is ReCaptcha, not Captcha!!!