Or, you can specify the drive by its unique volume id (which can either be found via the mountvol command, or picked from the list displayed by Duplicati.CommandLine.exe help backup) as \\?\volume id\Pictures.
Or, you can specify the drive by its unique volume id (which can either be found via the mountvol command, or picked from the list displayed by Duplicati.CommandLine.exe help backup) as \\?\volume id\Pictures.