This error message is highly likely because of the limitation in which you can’t use a Turnstile widget on several websites at the same time. If you want to use Turnstile on two separate domains, you will need to create 2 different Turnstile widgets.
If you have two different hostnames in the Turnstile widget, you will need to delete one of the hostnames and then add the Turnstile widget to your site. When that is done, you need to validate the server-side response.