Index: pyyaml/trunk/lib/yaml/composer.py
===================================================================
--- pyyaml/trunk/lib/yaml/composer.py	(revision 198)
+++ pyyaml/trunk/lib/yaml/composer.py	(revision 222)
@@ -9,5 +9,5 @@
     pass
 
-class Composer:
+class Composer(object):
 
     def __init__(self):
@@ -100,5 +100,5 @@
         if tag is None or tag == u'!':
             tag = self.resolve(MappingNode, None, start_event.implicit)
-        node = MappingNode(tag, {},
+        node = MappingNode(tag, [],
                 start_event.start_mark, None,
                 flow_style=start_event.flow_style)
@@ -106,11 +106,12 @@
             self.anchors[anchor] = node
         while not self.check_event(MappingEndEvent):
-            key_event = self.peek_event()
+            #key_event = self.peek_event()
             item_key = self.compose_node(node, None)
-            if item_key in node.value:
-                raise ComposerError("while composing a mapping", start_event.start_mark,
-                        "found duplicate key", key_event.start_mark)
+            #if item_key in node.value:
+            #    raise ComposerError("while composing a mapping", start_event.start_mark,
+            #            "found duplicate key", key_event.start_mark)
             item_value = self.compose_node(node, item_key)
-            node.value[item_key] = item_value
+            #node.value[item_key] = item_value
+            node.value.append((item_key, item_value))
         end_event = self.get_event()
         node.end_mark = end_event.end_mark