diff --git a/index.php b/index.php
index 1d523a3..f2410f7 100644
--- a/index.php
+++ b/index.php
@@ -337,7 +337,7 @@ function isLoggedIn()
 }
 
 // Force logout.
-function logout() { if (isset($_SESSION)) { unset($_SESSION['uid']); unset($_SESSION['ip']); unset($_SESSION['username']); unset($_SESSION['privateonly']); }  
+function logout() { if (isset($_SESSION)) { unset($_SESSION['uid']); unset($_SESSION['ip']); unset($_SESSION['username']); unset($_SESSION['privateonly']); }
 setcookie('shaarli_staySignedIn', FALSE, 0, WEB_PATH);
 }
 
@@ -907,7 +907,7 @@ function showRSS()
     else $linksToDisplay = $LINKSDB;
     $nblinksToDisplay = 50;  // Number of links to display.
     if (!empty($_GET['nb']))  // In URL, you can specificy the number of links. Example: nb=200 or nb=all for all links.
-    { 
+    {
         $nblinksToDisplay = $_GET['nb']=='all' ? count($linksToDisplay) : max($_GET['nb']+0,1) ;
     }
 
@@ -982,7 +982,7 @@ function showATOM()
     else $linksToDisplay = $LINKSDB;
     $nblinksToDisplay = 50;  // Number of links to display.
     if (!empty($_GET['nb']))  // In URL, you can specificy the number of links. Example: nb=200 or nb=all for all links.
-    { 
+    {
         $nblinksToDisplay = $_GET['nb']=='all' ? count($linksToDisplay) : max($_GET['nb']+0,1) ;
     }
 
@@ -1267,7 +1267,25 @@ function renderPage()
         // Get previous URL (http_referer) and add the tag to the searchtags parameters in query.
         if (empty($_SERVER['HTTP_REFERER'])) { header('Location: ?searchtags='.urlencode($_GET['addtag'])); exit; } // In case browser does not send HTTP_REFERER
         parse_str(parse_url($_SERVER['HTTP_REFERER'],PHP_URL_QUERY), $params);
-        $params['searchtags'] = (empty($params['searchtags']) ?  trim($_GET['addtag']) : trim($params['searchtags']).' '.trim($_GET['addtag']));
+
+        // Check if this tag is already in the search query and ignore it if it is.
+        // Each tag is always separated by a space
+        $current_tags = explode(' ', $params['searchtags']);
+        $addtag = true;
+        foreach ($current_tags as $value) {
+            if ($value === $_GET['addtag']) {
+                $addtag = false;
+                break;
+            }
+        }
+        // Append the tag if necessary
+        if (empty($params['searchtags'])) {
+            $params['searchtags'] = trim($_GET['addtag']);
+        }
+        else if ($addtag) {
+            $params['searchtags'] = trim($params['searchtags']).' '.trim($_GET['addtag']);
+        }
+
         unset($params['page']); // We also remove page (keeping the same page has no sense, since the results are different)
         header('Location: ?'.http_build_query($params));
         exit;
@@ -1558,7 +1576,7 @@ function renderPage()
             $title = (empty($_GET['title']) ? '' : $_GET['title'] ); // Get title if it was provided in URL (by the bookmarklet).
             $description = (empty($_GET['description']) ? '' : $_GET['description']); // Get description if it was provided in URL (by the bookmarklet). [Bronco added that]
             $tags = (empty($_GET['tags']) ? '' : $_GET['tags'] ); // Get tags if it was provided in URL
-            $private = (!empty($_GET['private']) && $_GET['private'] === "1" ? 1 : 0); // Get private if it was provided in URL 
+            $private = (!empty($_GET['private']) && $_GET['private'] === "1" ? 1 : 0); // Get private if it was provided in URL
             if (($url!='') && parse_url($url,PHP_URL_SCHEME)=='') $url = 'http://'.$url;
             // If this is an HTTP link, we try go get the page to extract the title (otherwise we will to straight to the edit form.)
             if (empty($title) && parse_url($url,PHP_URL_SCHEME)=='http')
@@ -1569,7 +1587,7 @@ function renderPage()
  					 {
                         // Look for charset in html header.
  						preg_match('#<meta .*charset=.*>#Usi', $data, $meta);
- 
+
  						// If found, extract encoding.
  						if (!empty($meta[0]))
  						{
@@ -1579,7 +1597,7 @@ function renderPage()
 							$html_charset = (!empty($enc[1])) ? strtolower($enc[1]) : 'utf-8';
  						}
  						else { $html_charset = 'utf-8'; }
- 
+
  						// Extract title
  						$title = html_extract_title($data);
  						if (!empty($title))