Summary

• application_namespace
• https://github.com/divio/django-cms/blob/develop/cms/admin/forms.py#L611
• using aldryn-apphook-config to have dropdowns in the page advanced settings apphook config field (but the problem likely also exists without aldryn-apphook-config)

Expected behaviour

• The editor should be able to add the AppHook configuration for app A with name 'default' to a page and then add an AppHook configuration for app B with name 'default' to another page.

Actual behaviour

• djangocms admin form returns 'An application instance with this name already exists.'
• the editor expects this to work

Environment

• Python version: any
• Django version: any
• django CMS version: 3.5.2

Proposed solution

• in _check_unique_namespace_instance include application_urls in filter:

 return Page.objects.drafts().on_site(self._site).filter(
            application_namespace=namespace,
            application_urls=application_urls,
        ).exclude(pk=self.instance.pk).exists()