diff --git a/lib/outputrenderers.php b/lib/outputrenderers.php
index 8bcd9b44e7a..add05e0a04a 100644
--- a/lib/outputrenderers.php
+++ b/lib/outputrenderers.php
@@ -776,7 +776,9 @@ class core_renderer extends renderer_base {
             if (!isset($CFG->additionalhtmlhead)) {
                 $CFG->additionalhtmlhead = '';
             }
-            $CFG->additionalhtmlhead .= '<meta name="robots" content="noindex" />';
+            if (stripos($CFG->additionalhtmlhead, '<meta name="robots" content="noindex" />') === false) {
+                $CFG->additionalhtmlhead .= '<meta name="robots" content="noindex" />';
+            }
         }
 
         if (!empty($CFG->additionalhtmlhead)) {