Profile Builder Spam Registrations

Hi,
I’m using the plugin “Profil builder” on my site and I have the problem that profiles are created automatically (in average 10 per Day). First I added a reCaptcha Field in the registration, but that didn’t changed anything. I made the Name and Surname required fields but the Spam accounts don’t have any. So I think the registrations request are sended directly to the server somehow.

Does someone know how to fix my problem?
Best regards,
Charles