Circuit breaker finder beeping on wrong breaker

I bought a circuit breaker finder to help map out my mess of a panel. I’m adding an outlet in my pantry so I first used it to identify the breaker for the circuit that I want to add to.

Circuit breaker finder beeped on breaker #6 - labeled kitchen. Makes perfect sense for the pantry! Turn it off, go up stairs, and the outlet still has power.

So I rescan and come up with the same thing. #6 beeping. So I turn off #6 and rescan. With #6 off, #20 beeps. So I turn #20 off and that ended up being the correct circuit.

So - why is it beeping on the wrong breaker, and only beeping on the correct one if the wrong one is off?