--- msvc9compiler.py.orig       2008-05-26 12:29:18.529288200 -0700
+++ msvc9compiler.py    2008-05-26 12:34:11.403841800 -0700
@@ -193,6 +193,17 @@
             reduced_paths.append(np)
     return reduced_paths
 
+def removeDuplicates(variable):
+    """Remove duplicate values of an environment variable.
+    """
+    oldList = variable.split(os.pathsep)
+    newList = []
+    for i in oldList:
+        if i not in newList:
+            newList.append(i)
+    newVariable = os.pathsep.join(newList)
+    return newVariable
+
 def find_vcvarsall(version):
     """Find the vcvarsall.bat file
 
@@ -257,7 +268,7 @@
         if key in interesting:
             if value.endswith(os.pathsep):
                 value = value[:-1]
-            result[key] = value
+            result[key] = removeDuplicates(value)
 
     if len(result) != len(interesting):
         raise ValueError(str(list(result.keys())))