not working with radio buttons

[frontendschlampe]

I use the current version 1.3 with Contao 4.9.28

I've created a fieldset with various input fields and radio buttons. I fill out the first fieldset and duplicate it. I fill out all fields of duplicate and send form. After reload I got an error on all mandatory radio buttons ind the duplicated fieldset, that I have to fill them. I check all radio buttons again, send form again and it works.