This cannot be changed by the wpDiscuz side. The second one is a hidden comment form. It is for reply box. It cannot be removed.
We may suggest them to use the unique ID (each wpDiscuz form has its own unique ID) and connect it with the fields they've created. They should already know the hook as far as they've used it.
In case you want to say thank you! 🙂 We'd really appreciate if you leave a good review on the plugin page. This is the best way to say thank you to this project and the support team.