I took my USB stick and created NTFS superfloppy with mkntfs -F -f /dev/sdc. The tool overwrote the whole first sector, including the bootstrap code area. Windows or another OS can assume for a while it's MBR and check its partition table area. This is what it will get:

As you can see fdisk is able to tell that "this doesn't look like a partition table". Windows will tell basically the same thing, then it will assume the sector is VBR, find NTFS signature in it, finally mount. Indeed ye olde Windows XP had no problem with this. Also my Kubuntu reported in dmesg:

but then KDE offered to mount it as superfloppy.

Note that any tool that probes for partition table reads in fact a fragment of bootstrap code from the VBR. This code is not needed for NTFS to work. I checked with hexdump that the fragment is not code; it looks like a set of text messages that will be displayed if I try to boot from this device, e.g.:

This means I can create a semi-valid partition table and it will only mangle with the text messages which I would probably never see anyway.

In Windows XP the drive behaves almost as your drive. Almost, because I got a letter assigned to the first partition. My real (superfloppy) NTFS filesystem is fresh and empty, yours is not. One of its sectors is interpreted as VBR for the first fake partition. Our sectors surely contain different data, maybe this is the reason. Nevertheless I believe I have just solved your mystery.

I took my USB stick and created an NTFS superfloppy with mkntfs -F -f /dev/sdc. The tool overwrote the whole first sector, including the bootstrap code area. Windows or another OS can assume for a while it's MBR and check its partition table area. This is what it will get:

As you can see fdisk is able to tell that "this doesn't look like a partition table". Windows will tell basically the same thing, then it will assume the sector is VBR, find an NTFS signature in it, finally mount. Indeed ye olde Windows XP had no problem with this. Also my Kubuntu reported in dmesg:

but then KDE offered to mount it as a superfloppy.

Note that any tool that probes my USB stick for a partition table reads in fact a fragment of the bootstrap code from the VBR. This code is not needed for NTFS to work. I checked with hexdump that the fragment is not code; it looks like a set of text messages that will be displayed if I try to boot from this device, e.g.:

This means I can create a semi-valid partition table and it will only mangle the text messages which I would probably never see anyway.

In Windows XP the drive behaves almost as your drive. Almost, because I got a letter assigned to the first partition. My real (superfloppy) NTFS filesystem is fresh and empty, yours is not. One of its sectors is interpreted as the VBR of the first fake partition. Our sectors surely contain different data, maybe this is the reason. Nevertheless I believe I have just solved your mystery.

Note that any tool that probes for partition table reads in fact a fragment of bootstrap code from the VBR. This code is not needed for NTFS to work. I checked with hexdump that the fragment isn't an executable code at all; it looks like a set of text messages that will be displayed if I try to boot from this device, e.g.:

This means I can create semi-valid partition table and it will only mangle with the text messages which I would probably never see anyway.

Note that any tool that probes for partition table reads in fact a fragment of bootstrap code from the VBR. This code is not needed for NTFS to work. I checked with hexdump that the fragment is not code; it looks like a set of text messages that will be displayed if I try to boot from this device, e.g.:

This means I can create a semi-valid partition table and it will only mangle with the text messages which I would probably never see anyway.

#Short explanation

#Long explanation

###MBR vs VBR

###The problem

#The fix

Short explanation

Long explanation

MBR vs VBR

The problem

The fix