Where did you see this?
Interestingly if you search Google for those flight numbers, the first hit is for the VA flight status page:
Flight information for QF8574/Today/plan | Flight Status | Virgin Australia Group of Airlines
Flight information for QF8566/Today | Flight Status | Virgin Australia Group of Airlines
Presumably it's some sort of QF positioning flight that DJ's website doesn't filter out.
If you do a route search for today, for flights from Perth to Sydney there are two QF flight numbers
QF8574
QF8566
Weird???
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