Originally Posted by
Tyrolean
Nope, they don't. They use two different AMADEUS systems. You can figure it out that Flights with QF and BA Segments have usually two Filekeys: One for BA and one for QF. Usually you can assign seats with the corresponding Filekeys in each website.
Whilst I agree with the two file keys reference in your post, you do realise Amadeus is effectively one monolithic platform hosted by Amadeus itself? It might be divided up between customers, but it's still the same platform. It's also the reason why QF and BA can see each others bookings as long as the appropriate PNR is given.
It's also effectively a single website but with customisations/configurations around each individual customer (eg QF).