I have been seeing strange tracks on my various Skyview receivers and it now appears that it is caused by two aircraft with the same ICAO number in view at the same time
VH-PPY
and VH-UUQ
EDIT
Both aircraft are owned by the same company
That ICAO address looks like a junk test address anyway (123456, really? - it’s not even in the right country block for a VH registration) - so it’s just badly configured transponders.
One more example
https://flightaware.com/live/flight/N9081U/history/20190615/1009Z
I regularly see 123456, 000000 and 246810.
123456 is the only one I have caught with two aircraft simultaneously sharing an ICAO registration.
123456 shows a Russian Federation flag in Skyview.
I’ve passed the information on to my Air Services contact but he seems to think that ATC will just filter it out unless it is in controlled airspace in which case it is tracked on RADAR and filtered out of their ADS-B tracking.
It too will be fixed in time.
S.
Russian technicians are not particularly concerned about entering any codes. Typically, these planes do not leave the borders of Russia.
They are Australian planes with Australian registrations.
It appears someone configured their ADSB transmitters with an ICAO number of 123456 which is within the Russian allocation.
Such is life.
S.