diff --git a/apps/activity/views.py b/apps/activity/views.py
index 7829a2ee..50607ceb 100644
--- a/apps/activity/views.py
+++ b/apps/activity/views.py
@@ -152,9 +152,11 @@ class ActivityDetailView(ProtectQuerysetMixin, LoginRequiredMixin, MultiTableMix
     def get_tables_data(self):
         return [
             Guest.objects.filter(activity=self.object)
-                         .filter(PermissionBackend.filter_queryset(self.request, Guest, "view")),
+                         .filter(PermissionBackend.filter_queryset(self.request, Guest, "view"))
+                         .distinct(),
             self.object.opener.filter(activity=self.object)
-                              .filter(PermissionBackend.filter_queryset(self.request, Opener, "view")),
+                              .filter(PermissionBackend.filter_queryset(self.request, Opener, "view"))
+                              .distinct(),
         ]
 
     def render_to_response(self, context, **response_kwargs):
@@ -309,7 +311,7 @@ class ActivityInviteView(ProtectQuerysetMixin, ProtectedCreateView):
     @transaction.atomic
     def form_valid(self, form):
         form.instance.activity = Activity.objects\
-            .filter(PermissionBackend.filter_queryset(self.request, Activity, "view")).get(pk=self.kwargs["pk"])
+            .filter(PermissionBackend.filter_queryset(self.request, Activity, "view")).distinct().get(pk=self.kwargs["pk"])
         return super().form_valid(form)
 
     def get_success_url(self, **kwargs):