Barry,
There is no "completed" state for the documents in the Capture database. Once they are completed, they are deleted, and it's meant to work this way. The idea is that it will remain opened until it is signed and the Pen has been docked. Then it will process the pgc and close the document once it's done, as it's been signed and shouldn't be reused again.
If all you want is a backup of the document, maybe you can just use a send to folder to send the final pdf file in a folder where you can archive your jobs.
Regards,
Raphaël Lalonde Lefebvre