When a safe is changed or deleted, a single backup copy of the safe is made (either locally or in iCloud, depending upon the location). This backup copy won’t be overwritten within a 24 hour period.
Backups can be restored from the Restore Backups Settings menu. Backups are listed, along with the backup time, and may be restored by selecting and then tapping Restore. Backups may be removed by swiping the listed backup to the left and selecting Delete.
Restored backup’s are renamed to avoid overwriting an existing safe.