diff --git a/src/SSDP/Device.php b/src/SSDP/Device.php
index dc05740..a0570a6 100644
--- a/src/SSDP/Device.php
+++ b/src/SSDP/Device.php
@@ -47,7 +47,11 @@ class Device
 
     public static function createFromSchema($url, $ip)
     {
-        $xml = simplexml_load_file($url);
+        $xml = @simplexml_load_file($url);
+        if (empty($xml)) {
+            error_log("Unable to retrieve UPnP schema from {$url}");
+            return null;
+        }
         
         $spec = $xml->children('urn:schemas-upnp-org:device-1-0');
         if (count($spec)>0) {
diff --git a/src/SSDP/Discovery.php b/src/SSDP/Discovery.php
index 97b901d..670a2bb 100644
--- a/src/SSDP/Discovery.php
+++ b/src/SSDP/Discovery.php
@@ -47,8 +47,12 @@ class Discovery implements IteratorAggregate
         foreach ($responses as $response) {
             // Add the relevant responses to the list
             if ($response instanceof MSearchResponse) {
+                $loc = $response->getLocation();
+                if (array_key_exists($loc, $this->devices)) {
+                    continue;
+                }
                 $device = Device::createFromSchema($response->getLocation(), $response->getIp());
-                $this->devices[] = $device;
+                $this->devices[$loc] = $device;
             }
         }