--- Request2.php.orig	2010-06-21 15:01:59.000000000 +0200
+++ Request2.php	2010-06-21 15:04:34.000000000 +0200
@@ -469,12 +469,17 @@ class HTTP_Request2 implements SplSubjec
             if (preg_match(self::REGEXP_INVALID_TOKEN, $name)) {
                 throw new HTTP_Request2_Exception("Invalid header name '{$name}'");
             }
+
             // Header names are case insensitive anyway
             $name = strtolower($name);
             if (null === $value) {
                 unset($this->headers[$name]);
             } else {
-                $this->headers[$name] = $value;
+                if (!isset($this->headers[$name])) {
+                    $this->headers[$name] = $value;
+                } else {
+                    $this->headers[$name] .= ', ' . $value;
+                }
             }
         }