I didn't want to say anything as I thought I'd be called a loonie!
My wife and I saw this pass over Sydney last week. It was definitely two easily definable circles.
Like you, I thought it was ISS at first, but then it got a whole lot brighter and the two circles
really became obvious. It looked far bigger than the ISS. It was visible for maybe 15 seconds
before it faded away.
I searched on heavens-above but couldn't find anything visual at that time and place.
A quick bit of searching has me thinking it might be the Chinese Tiangong 1 station with the
Shenzhou spacecraft docked to it.