diff --git a/admin/preprint_providers/forms.py b/admin/preprint_providers/forms.py
index 1393aae41ef..cb7a0f1b1e9 100644
--- a/admin/preprint_providers/forms.py
+++ b/admin/preprint_providers/forms.py
@@ -116,10 +116,10 @@ def __init__(self, *args, provider_groups=None, **kwargs):
         super().__init__(*args, **kwargs)
 
         provider_groups = provider_groups or Group.objects.none()
-        self.fields['group_perms'] = forms.ModelMultipleChoiceField(
+        self.fields['group_perms'] = forms.ModelChoiceField(
             queryset=provider_groups,
             required=False,
-            widget=forms.CheckboxSelectMultiple
+            widget=forms.RadioSelect
         )
 
     user_id = forms.CharField(required=True, max_length=5, min_length=5)
diff --git a/admin/preprint_providers/views.py b/admin/preprint_providers/views.py
index 4c7439f4554..d841981fe84 100644
--- a/admin/preprint_providers/views.py
+++ b/admin/preprint_providers/views.py
@@ -481,10 +481,14 @@ def form_valid(self, form):
         if not osf_user:
             raise Http404(f'OSF user with id "{user_id}" not found. Please double check.')
 
-        for group in form.cleaned_data.get('group_perms'):
-            self.target_provider.add_to_group(osf_user, group)
+        if osf_user.has_groups(self.target_provider.group_names):
+            messages.error(self.request, f'User with guid: {user_id} is already a moderator or admin')
+            return super().form_invalid(form)
 
+        group = form.cleaned_data.get('group_perms')
+        self.target_provider.add_to_group(osf_user, group)
         osf_user.save()
+
         messages.success(self.request, f'Permissions update successful for OSF User {osf_user.username}!')
         return super().form_valid(form)
 
diff --git a/admin/providers/views.py b/admin/providers/views.py
index e42d25bb5c9..d21cd65a93b 100644
--- a/admin/providers/views.py
+++ b/admin/providers/views.py
@@ -29,8 +29,7 @@ def post(self, request, *args, **kwargs):
             messages.error(request, f'User for guid: {data["add-moderators-form"][0]} could not be found')
             return redirect(f'{self.url_namespace}:add_admin_or_moderator', provider_id=provider.id)
 
-        groups = [provider.format_group(name) for name in provider.groups.keys()]
-        if target_user.has_groups(groups):
+        if target_user.has_groups(provider.group_names):
             messages.error(request, f'User with guid: {data["add-moderators-form"][0]} is already a moderator or admin')
             return redirect(f'{self.url_namespace}:add_admin_or_moderator', provider_id=provider.id)