It seems that the updated version is the one that has gone to the archives rather than the older version - the older version remained on the laptop. It was only when searching for the version that I knew I had updated that I discovered this issue. Also, I believe that all the changes were made on the same laptop - not a peer. In any event, irrespective of which device is used to update the document, should the changes not be synced across all peers and thus the latest version be saved on every device?