I'm not sure what the best way to record from two headsets into your iPhone would be, you wouldn't be able to connect both headsets directly to the iPhone to record and it's possible even with adapters you would not be able to do so.
You would likely need to find a way to take the audio from the heli, to the iPhone as both headsets will be connected to the heli directly. I wouldn't be able to advise on how to do this sadly, but if any other members of the Community have had any experience recording audio from multiple A20 headsets, it would be great to hear from you how you did it!
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