Recreating backups

I have a Raspberry Pi 4 running Raspberry Pi OS Lite (64-bit), Openmediavault and Duplicati. I have three SSD drives; (i) a drive containing the Pi OS and other installed software, (ii) a data drive containing the OMV shared folders and (iii) another drive containing the Duplicati backups.

Until recently everything was working OK and I had a Duplicati backup working OK.

A few days ago the drive holding the OS, OMV and Duplicati (drive (i)) failed so I have had to rebuild the system.

I now have the system running again with OMV and Duplicati installed. This time I have the Pi booting from a USB SSD and not from a sdcard.

As this is new installation of Duplicati I have not yet created any backups.

I do have the original drive (iii) which contains the Duplicati backup.

Is there anyway I can restore my data drive (drive (ii)) from the backup drive (drive (iii)) even though I do not have any backups created in Duplicati?

if you have encrypted your backup and not saved the encryption key you are out of luck, sorry.
If you have disabled encryption when setting up your backup, or saved at least the key, you can always import direct from the backup, or even recreate a new job with similar parameters, do a recreate database, and restore from the job.
Obviously for this to work you need a working backup, if the disk has gone bad, it will be difficult to restore anything from it. Also if you recreate a new job, do not setup an automatic backup before having succeeded restoring your data.

Also don’t forget in the future that you can export a job as a Json file. And that best pratice for backup nowadays are the 3-2-1 rule (IIRC 3 backups on 2 different devices, 1 being off-site).
Having all your data on a single backup support is not recommended.