I'm on the latest version. Is it just random which one plays? And do you need to do something and come back to re-trigger the randomness?
it is random every time you enter the room location but I do remember a solo scene having both A and B triggers go to the B scene.
I found that this still occurred on version 0.09B (previously I was on 0.08B). I'm not sure if it's already fixed on the Patreon-only version. But I decided to debug it myself and managed to find and fix it in the Renpy code, and filed a bug report.
it should be, I'm guessing I fixed it in 0.10 or 0.11 at least.