Index: D:/boost/boost.build/libs/serialization/src/extended_type_info.cpp
===================================================================
--- D:/boost/boost.build/libs/serialization/src/extended_type_info.cpp	(revision 138997)
+++ D:/boost/boost.build/libs/serialization/src/extended_type_info.cpp	(revision 138998)
@@ -78,6 +78,8 @@
 BOOST_SERIALIZATION_DECL(void)  
 extended_type_info::key_register(const char *key) {
     assert(NULL != key);
+    if (m_key)
+      return;
     m_key = key;
     singleton<detail::ktmap>::get_mutable_instance().insert(this);
 }