I've seen many questions on this topic from the Symantec Connect forums... People wonder what happens when an archive is exported back to Exchange, or out to a PST file. Some, well, many people, expect that exporting the archive does what the name implies: 'Moves' all the data back to the chosen location. That's not the case though. When you export an archive, the items in the archive remain unchanged.
There is one subtle exception. As you can see from this screenshot if you export all items you don't get any delete options:
On the other hand if you 'export all items from this root folder path' and choose from the root (ie \) folder you can have the option to delete the archived items too: