The UrBackup server can make a backup of it's own databases onto your backup volume, check the option "Automatically backup UrBackup database" in your Server settings.
Your backup volume can subsequently be snapshotted and shuttled over to another server (and another, and another, however many you want) if you use a filesystem like ZFS. Or you could do an rsync or whatever other mechanism you want to use to backup your backup volume.
For file based backups, the data is readily readable as a regular file structure, even if you don't (want to) use UrBackup for restores, you can read it with a regular file browser. For image based backups, it seems to be stored in a format that is readable by non-UrBackup imaging programs (there is a LiveCD for example) and thus you could mount it or restore it.