[Mailman-Users] importing held messages from dr system

Is there a way to import held messages from one mail system to another? I have multiple mailman servers but only manage them from one web interface. When a message gets held on one of the mail servers that is not primary it is not accessible via the web interface. I've tried simply copying the pck file over, but they aren't recognized. A restart of mailman doesn't do the trick either. I imagine that I would need to initiated a rebuild of a database.