Two NTFS partitions = "More than one Windows partitions are found"

I've configured my Mac Pro with active and cloned backups of each boot volume [over 3 physical drive] E.g. for XP, there is


XP, NTFS 50GB

XP Bak, NTFS 50GB

Though I've not used Boot Camp except for drivers, I successfully created a 3 volume drive with one NTFS = "XP Bak", installed XP, then created a new VM via the "Use Boot Camp" option.

After testing direct boot and Parallels VM I cloned the "XP Bak" volume to an image using Acronis True Image v10. This is to become the "XP" volume.

I then created the 2 partitions on another physical drive, including the second NTFS = "XP". When I started the XP Bak VM I get the "More than one Windows partitions are found."

I unmounted the new NTFS drive "XP". Restart Parallels = same error.

I see others have had exactly the same problem when the config includes more than one FAT32 or NTFS volume. But I've not yet found a clear fix.

Any suggestions mucho appreciated.