A rare North Borneo cover ???

I'm glad none of my friends went in for this RARE cover. THE REGISTER LABEL MAY NOT BE PART OF THE ORIGINAL COVER, IT MAY BE ADDED TO THE COVER AFTER THE STAMPS BEING CANCELLED. UNLESS THE POST MARK WERE FROM SYDNEY, THE REGISTER LABEL WASN'T VERY CONVINCING. THE SENDER'S ADDRESS BLACKEN OUT WHICH DID NOT HELP.

bury1883 phoned up last night, telling me his failed challenge with a 'richman', gantianexpress :) but he did make him paid an extra $100 ! I thought the 3rd highest bidder, owley1879's bidding was closer to my estimate. The next time bury1883 come to KK, he'll be chased by gantianexpress's dogs, that may be sent out to 'search & destroy', so don't come to my home until you're secured !!! Shall I show the cover in my next posting ??? ONLY ON POPULAR REQUESTS.