Check Box Issue with Form Maker Plugin

Dear all,

I have some issues with the sporting theme implemented checkbox feature. I want to setup a form with form maker plugin and there will appear two check boxes instead of one. One from theme site and one from plugin site. I tried to use a wordpress theme (twenty twenty) and the checkbox feature of plugin worked fine.

Please watch this site for more information:

http://www.bv21.de/mitgliedsantrag-online/

Best regards
Vadim