Hidden & Duplicate rules prevents migration of BRMS repository via export/import

Issue

We have hidden and duplicate rules in our repository, which is preventing us migrating it to a new release of BRMS.

A 'hidden' rule is one that does not appear in the Knowledge Base, but does appear in a snapshot we take of that knowledge base.

There are duplicate versions of this asset:
/drools:repository[29]/drools:package_area/MyRepo/assets/MyAsset

If we try to re-import this repository we see the following error:
2011-05-18 13:17:59,168 INFO  [STDOUT] ERROR 18-05 13:17:59,168 (RulesRepository.java:importRulesRepositoryFromStream:989)       javax.jcr.ItemExistsException: /drools:repository[29]/drools:package_area/MyRepo/MyAsset
2011-05-18 13:17:59,231 ERROR [org.apache.catalina.core.ContainerBase] Servlet.service() for servlet RepositoryBackupServlet threw exception
javax.jcr.ItemExistsException: /drools:repository[29]/drools:package_area/MyRepo/assets/MyAsset
at org.apache.jackrabbit.core.xml.WorkspaceImporter.startNode(WorkspaceImporter.java:436)
.....more......

This rule is not listed in the Knowledge Base and can't be found by searching.
However, it does occur twice in the exported XML repository.

Both nodes are named, MyAsset, but they have different titles.