Originally Posted by
Schwann
BA and QR both use the same back end booking management system (Amadaeus), but I believe when booking QR flights with BA codes/via BA.com there is also a QR reference generated. That was the case when I booked via BA.com for QR operated flights although it was a few years ago.
This is no longer the case even for codeshare bookings with BA/QR, it is usually just a single PNR these days. You're right though, previously there used to be a separate QR and BA PNR as recent as 2019. Guessing they've had some background IT updates since then because my following BA/QR booking was then in late 2021 and it was the same PNR, another trip in summer 2022 was the same and an upcoming booking in 2023 is the same also.