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
@@ -245,9 +245,18 @@
         $menu->addItem($item);
       }
 
+      $second_factor_text = null;
+      if ($viewer->getIsEnrolledInMultiFactor()) {
+        $second_factor_text = pht(
+          'Note: You already have an Auth Factor configured. Adding a '.
+          'second factor will require you to always provide both Auth '.
+          'Factors instead of selecting one of your Auth Factors.');
+      }
+
       return $this->newDialog()
         ->setTitle(pht('Choose Factor Type'))
         ->appendChild($menu)
+        ->appendParagraph($second_factor_text)
         ->addCancelButton($cancel_uri);
     }