Orsetto, you were on the money. I reached out to hasselblad - though the service department was a bit puzzled at first, they did some digging and concluded it was probably an opto fiber screen installed into an Acute Matte D frame at some point by a technician.
I ended up returning the screen. I paid Acute Matte D price for it, so definitely overpaid. Seller was very understanding and apologized - it was most likely an honest mistake.
I need an Acute Matte or Acute Matte D so that my PME51 finder meters properly. Ended up going for an AMD with split image and prism. Really debated between the focus precision of the prism/split image version versus the clean, undistracting plain AMD, which I imagine is just a joy to look through. The prism version just barely edged out the plain version in the end. If I'm shooting 120 I want to be assured that I can focus very precisely.