diff --git a/.gsoc/todo.txt b/.gsoc/todo.txt
index 570b1dd9d..959835c0c 100644
--- a/.gsoc/todo.txt
+++ b/.gsoc/todo.txt
@@ -7,10 +7,3 @@ info about setup script in prefs manage, it seems many people still don't know i
 
 
 show blacklist (and debug?) on prefs manage page
-
-
-/*        if (!isset($this->persistKeys[$canonical_path])
-                // equality but only if both values are numeric or not numeric, allows to skip 0 == 'auto'
-                && (($value == $default_value && !(is_numeric($value) xor is_numeric($value)))
-                    ||
-                    (empty($value) && empty($default_value)))) {*/
diff --git a/libraries/config/FormDisplay.class.php b/libraries/config/FormDisplay.class.php
index a176c3bdf..5a08f5e87 100644
--- a/libraries/config/FormDisplay.class.php
+++ b/libraries/config/FormDisplay.class.php
@@ -461,9 +461,14 @@ class FormDisplay
      */
     private function _validateSelect(&$value, array $allowed)
     {
+        $value_cmp = is_bool($value)
+            ? (int) $value
+            : $value;
         foreach ($allowed as $vk => $v) {
-            // force string comparison so that 0 isn't equal to any string
-            if ((string)$value == (string)$vk) {
+            // equality comparison only if both values are numeric or not numeric
+            // (allows to skip 0 == 'string' equalling to true) or identity (for string-string)
+            if (($vk == $value && !(is_numeric($value_cmp) xor is_numeric($vk)))
+                    || $vk === $value) {
                 settype($value, gettype($v));
                 return true;
             }
diff --git a/prefs_manage.php b/prefs_manage.php
index 3df224988..bd085593e 100644
--- a/prefs_manage.php
+++ b/prefs_manage.php
@@ -87,14 +87,16 @@ if (isset($_POST['submit_export']) && filter_input(INPUT_POST, 'export_type') ==
             }
         }
         $cf = ConfigFile::getInstance();
-        if (empty($_POST['import_merge'])) {
-            $cf->resetConfigData();
+        $new_config = $cf->getFlatDefaultConfig();
+        if (!empty($_POST['import_merge'])) {
+            $new_config = array_merge($new_config, $cf->getConfigArray());
         }
+        $new_config = array_merge($new_config, $config);
         $_POST_bak = $_POST;
-        foreach ($cf->getFlatDefaultConfig() as $k => $v) {
+        foreach ($new_config as $k => $v) {
             $_POST[str_replace('/', '-', $k)] = $v;
         }
-        $_POST = array_merge($_POST, $config);
+        $cf->resetConfigData();
         $all_ok = $form_display->process(true, false);
         $all_ok = $all_ok && !$form_display->hasErrors();
         $_POST = $_POST_bak;