Surely, someone must know..
Yes, but sometimes shit happens (Like ransome-ware attacks
No matter how you transfer the signal (copper, radio or whatever), mixing two signals will produce a third.
Assuming just a whistle (a fairly close sine wave) which hit the two michrophones at an angle from their center, the sound waves will hit at different phases and this will produce a third signal. If you draw two sines with their phases eg. 30° apart, it should be clear to you.
Whether it will be an issue in your situation is hard to say, but if you just want to listen to the sound it's probably OK (if not, just settle for a single mike).