Index: course/modduplicate.php
===================================================================
--- course/modduplicate.php	(revision 16884)
+++ course/modduplicate.php	(revision )
@@ -54,6 +54,20 @@
 
 $output = $PAGE->get_renderer('core', 'backup');
 
+$a          = new stdClass();
+$a->modtype = get_string('modulename', $cm->modname);
+$a->modname = format_string($cm->name);
+
+if (!plugin_supports('mod', $cm->modname, FEATURE_BACKUP_MOODLE2)) {
+    echo $output->header();
+    echo $output->notification(get_string('duplicatenosupport', 'core', $a));
+    echo $output->continue_button(
+        new moodle_url('/course/view.php#section-' . $cm->sectionnum, array('id' => $course->id))
+    );
+    echo $output->footer();
+    die;
+}
+
 // backup the activity
 
 $bc = new backup_controller(backup::TYPE_1ACTIVITY, $cm->id, backup::FORMAT_MOODLE,
@@ -125,10 +139,6 @@
     fulldelete($backupbasepath);
 }
 
-$a          = new stdClass();
-$a->modtype = get_string('modulename', $cm->modname);
-$a->modname = format_string($cm->name);
-
 echo $output->header();
 
 if ($newcmid) {
Index: lang/en/moodle.php
===================================================================
--- lang/en/moodle.php	(revision 16884)
+++ lang/en/moodle.php	(revision )
@@ -465,6 +465,7 @@
 $string['duplicateconfirm'] = 'Are you sure you want to duplicate {$a->modtype} \'{$a->modname}\' ?';
 $string['duplicatecontcourse'] = 'Return to the course';
 $string['duplicatecontedit'] = 'Edit the new copy';
+$string['duplicatenosupport'] = '\'{$a->modname}\' activity could not be duplicated because the {$a->modtype} module does not support backup and restore.';
 $string['duplicatesuccess'] = '{$a->modtype} \'{$a->modname}\' has been duplicated successfully';
 $string['duplicatinga'] = 'Duplicating: {$a}';
 $string['edhelpaspellpath'] = 'To use spell-checking within the editor, you MUST have <strong>aspell 0.50</strong> or later installed on your server, and you must specify the correct path to access the aspell binary.  On Unix/Linux systems, this path is usually <strong>/usr/bin/aspell</strong>, but it might be something else.';
Index: course/lib.php
===================================================================
--- course/lib.php	(revision 16884)
+++ course/lib.php	(revision )
@@ -3262,6 +3262,14 @@
             $plugins .= $function($mod);
         }
     }
+    if (plugin_supports('mod', $mod->modname, FEATURE_BACKUP_MOODLE2)) {
+        $duplicate = '<a class="editing_duplicate" title="'.$str->duplicate.'" href="'.$path.'/mod.php?duplicate='.$mod->id.
+                     '&amp;sesskey='.$sesskey.$section.'"><img'.
+                     ' src="'.$OUTPUT->pix_url('t/copy') . '" class="iconsmall" '.
+                     ' alt="'.$str->duplicate.'" /></a>'."\n";
+    } else {
+        $duplicate = '';
+    }
 
 
     return '<span class="commands">'."\n".$leftright.$move.
@@ -3269,10 +3277,7 @@
            '&amp;sesskey='.$sesskey.$section.'"><img'.
            ' src="'.$OUTPUT->pix_url('t/edit') . '" class="iconsmall" '.
            ' alt="'.$str->update.'" /></a>'."\n".
-           '<a class="editing_duplicate" title="'.$str->duplicate.'" href="'.$path.'/mod.php?duplicate='.$mod->id.
-           '&amp;sesskey='.$sesskey.$section.'"><img'.
-           ' src="'.$OUTPUT->pix_url('t/copy') . '" class="iconsmall" '.
-           ' alt="'.$str->duplicate.'" /></a>'."\n".
+           $duplicate.
            '<a class="editing_delete" title="'.$str->delete.'" href="'.$path.'/mod.php?delete='.$mod->id.
            '&amp;sesskey='.$sesskey.$section.'"><img'.
            ' src="'.$OUTPUT->pix_url('t/delete') . '" class="iconsmall" '.