diff --git a/src/applications/settings/panel/PhabricatorMultiFactorSettingsPanel.php b/src/applications/settings/panel/PhabricatorMultiFactorSettingsPanel.php
--- a/src/applications/settings/panel/PhabricatorMultiFactorSettingsPanel.php
+++ b/src/applications/settings/panel/PhabricatorMultiFactorSettingsPanel.php
@@ -245,10 +245,21 @@
         $menu->addItem($item);
       }
 
-      return $this->newDialog()
-        ->setTitle(pht('Choose Factor Type'))
-        ->appendChild($menu)
-        ->addCancelButton($cancel_uri);
+      if ($viewer->getIsEnrolledInMultiFactor()) {
+        return $this->newDialog()
+          ->setTitle(pht('Choose Factor Type'))
+          ->appendChild($menu)
+          ->appendParagraph(pht(
+            'Note: You already have an Auth Factor configured. Adding '.
+            'another factor will require you to always provide all Auth '.
+            'Factors instead of selecting one of your Auth Factors.'))
+          ->addCancelButton($cancel_uri);
+      } else {
+        return $this->newDialog()
+          ->setTitle(pht('Choose Factor Type'))
+          ->appendChild($menu)
+          ->addCancelButton($cancel_uri);
+      }
     }
 
     // NOTE: Beyond providing guidance, this step is also providing a CSRF gate