Not looking for an exact answer here, merely inquisitive.
I have two Pi Zeros, both running PiAware and both also appear to have identical ADS-B tuners with stock antenna sitting on a tin can. One is one side of my house and the other is on the opposite. Both antenna are indoors on a window sill.
No known configuration changes made by me.
Basically they record the same aircraft with subtle differences.
The daily aircraft count is quite close but one appears to register far more messages per second than the other. Normally double but often triple or more.
Why might this be?