
It turns out this is not a bug, but a feature: Spanning Backup calls this “ non-destructive restore,” and it means Spanning Backup never deletes your existing contacts when it restores an old backup, even if duplicates are created.

SPANNING BACKUP GMAIL ANDROID
I realized this had happened when all my contacts started showing up twice on my Android phone, though at first I thought something must be wrong with the phone. Spanning Backup then proceeded to restore all of my contacts, even those that were not deleted, creating over 360 duplicate contacts. After hunting around the snapshot list for a snapshot that contained the group I needed, I ended up clicking the earliest snapshot thinking that snapshot surely has the contact I need. Instead, it let me pick a contact group to restore–and it wasn’t the group the contact I deleted was in. I expected Spanning to show me contacts deleted or modified since that backup was made. Not ideal, but not too confusing: I clicked the latest successful backup, taken before I deleted the contact. When I tried to restore it, Spanning Backup presented me with a list of backup timestamps showing the dates of recent successful backups. To test Spanning Backup, I deleted a Google contact. Speaking of restoration, the data restoration interface leaves a lot to be desired. You don’t get to download any of it to your own computer, and you can only restore it to the account from which it was backed up. All information is saved over the cloud, onto Spanning Backup’s own servers.

The information Spanning Backup saves is extensive: Gmail, Google Docs, Google Calendar, and Google Contacts, right down to contact images.
