United Nations FDC 1989 Brunei

On 22nd September 1989, the United Nations issued this first day cover. I am not sure whether the UN only issued one first day cover for Brunei only on this day or whether the UN issued many other first day cover on the same day - all based on the nations' flags. This flag design is surprisingly the only flag design that any stamp, Brunei or otherwise has depicted. Not a single stamp issued by