Hello bjorn, welcome to our community!
Thank you for contacting us about this. It is indeed unusual, since their performance should be the same if they are located in the same spot (or, at least, close enough that the difference between the two is not created by their different positioning, as I am sure you have already checked).
Could you please post a couple of pictures for each BOOM, to verify that the microbarograph filter (the red one, if you haven’t switched for your research purposes to the yellow one) is in the correct place?
Could you also post sample datasets (even screenshots are all right, as long they show the discrepancy you are describing) and the logs from both BOOMs? You can download the log files following these instructions: Please read before posting!
Thank you!