I’ve noticed this since the 17th of November, and had assumed it would pass over time. However, it appears to be firmly in place so I figured I’d raise it here.
For every Air New Zealand flight (callsign ANZ) there is also a clone appearing with the callsign EAG and the same flight number, but it’s not an Eagle Air flight. Eagle Air operate a feet of Beech 1900D aircraft on domestic operations between mostly small regional airports in New Zealand (classic flight here flightaware.com/live/flight/EAG187)
Yet if you visit flightaware.com/live/flight/ANZ842 and when the flight is actually in the air, you see it (at least) twice. Once from the actual data of ANZ842, and another from the estimated position of EAG842. As far as I can tell, this applies to every ANZ flight in air. It’s making busy times impractical to follow in New Zealand, as there’s so many clones you often can’t make out individual targets.
I’m not sure whether Airways New Zealand changed something in their data feed around the 17th, or whether an update has occurred on the website around that time, but I thought I’d mention it here in the hope it can get addressed.