diff -r dec10a3eb95f Doc/library/cookie.rst
--- a/Doc/library/cookie.rst	Sat Feb 23 08:19:00 2013 +0200
+++ b/Doc/library/cookie.rst	Sat Feb 23 17:08:03 2013 +0100
@@ -145,7 +145,8 @@
 .. method:: BaseCookie.load(rawdata)
 
    If *rawdata* is a string, parse it as an ``HTTP_COOKIE`` and add the values
-   found there as :class:`Morsel`\ s. If it is a dictionary, it is equivalent to::
+   found there as :class:`Morsel`\ s. In case the string contains duplicate
+   keys, the first value is used.  If it is a dictionary, it is equivalent to::
 
       for k, v in rawdata.items():
           cookie[k] = v
diff -r dec10a3eb95f Lib/Cookie.py
--- a/Lib/Cookie.py	Sat Feb 23 08:19:00 2013 +0200
+++ b/Lib/Cookie.py	Sat Feb 23 17:08:03 2013 +0100
@@ -226,6 +226,7 @@
 _semispacejoin = '; '.join
 _spacejoin = ' '.join
 
+
 #
 # Define an exception visible to External modules
 #
@@ -641,6 +642,7 @@
         i = 0            # Our starting point
         n = len(str)     # Length of string
         M = None         # current morsel
+        keys = set()     # Keys found in string
 
         while 0 <= i < n:
             # Start looking for a cookie
@@ -650,6 +652,13 @@
             K,V = match.group("key"), match.group("val")
             i = match.end(0)
 
+            # If a key is duplicated in the string, 
+            # only use the first value and ignore duplicates
+            if K in keys:
+                continue
+            else:
+                keys.add(K)
+
             # Parse the key, value in case it's metainfo
             if K[0] == "$":
                 # We ignore attributes which pertain to the cookie
diff -r dec10a3eb95f Lib/test/test_cookie.py
--- a/Lib/test/test_cookie.py	Sat Feb 23 08:19:00 2013 +0200
+++ b/Lib/test/test_cookie.py	Sat Feb 23 17:08:03 2013 +0100
@@ -21,6 +21,13 @@
               'output': 'Set-Cookie: keebler="E=mc2; L=\\"Loves\\"; fudge=\\012;"',
             },
 
+            # Check that first value for a duplicate key is used
+            { 'data': 'duplicate=first; duplicate=second',
+              'dict': {'duplicate':'first'},
+              'repr': "<SimpleCookie: duplicate='first'>",
+              'output': 'Set-Cookie: duplicate=first',
+            },
+
             # Check illegal cookies that have an '=' char in an unquoted value
             { 'data': 'keebler=E=mc2',
               'dict': {'keebler' : 'E=mc2'},