I think this *may* be a rotor to adapt a Jag cap for 911 twin plug use.
https://www.ebay.com/itm/PORSCHE-911-RS-RSR-CORRECT-DISTRIBUTOR-ROTOR-NEW-/310931967059?hash=item4864fd4c53:g:ZaEAAOSw5cNYFge X&vxp=mtr
Another contact who may be able to help is jpnovak here on the forum.