diff --git a/README.txt b/README.txt
index babb09e..b46e839 100644
--- a/README.txt
+++ b/README.txt
@@ -4,7 +4,7 @@ Donate link: http://paypal.me/anex
 Tags: forms, referer, tracking
 Requires at least: 4.5.0
 Tested up to: 4.7
-Stable tag: 1.1.0
+Stable tag: 1.1.1
 License: GPLv2 or later
 License URI: http://www.gnu.org/licenses/gpl-2.0.html
 
@@ -25,6 +25,9 @@ Saves Referers within a Cookie and submits them within hidden fields from a (gra
 
 == Changelog ==
 
+= 1.1.1 - 04/04/2017 =
+* Improved parameter check. Check now to submit only unique values per parameter
+
 = 1.1.0 - 28/03/2017 =
 * Improved "merging" of parameters with the same key; now getting displayed grouped.
 
diff --git a/includes/engine.php b/includes/engine.php
index 7fd74bb..e24263e 100644
--- a/includes/engine.php
+++ b/includes/engine.php
@@ -81,6 +81,18 @@ protected function _hash($str) {
         return hash_hmac($this->_algo, $str, NONCE_KEY);
     }
 
+    protected function _arrayUniqueRecursive($array) {
+
+        $result = array_map("unserialize", array_unique(array_map("serialize", $array)));
+
+        foreach ($result as $key => $value) {
+            if(is_array($value))
+                $result[$key] = $this->_arrayUniqueRecursive($value);
+        }
+
+        return $result;
+    }
+
     public function updateCookie() {
 
         $strategy = $this->_plugin->getOption('cookie_merge_strategy');
@@ -94,7 +106,7 @@ public function updateCookie() {
         $data = $this->getUrlData();
 
         if($cookieData !== false && $strategy == 'merge')
-            $data = array_merge_recursive($cookieData, $data);
+            $data = $this->_arrayUniqueRecursive(array_merge_recursive($cookieData, $data));
 
         $data['timestamp'] = time();