You've updated A1, a persistent entity, so when you flush the Persistence Context, i the changes get persisted. If this was just regular java objects, you wouldn't expect the above to work... so, redesign so it would work with plain java objects and then add in your pesistence - *don't* use the PC to play tricks!
I know they are persisted.
But I don't have much experience with EJB3, JPA, Hibernate...
I hoped that maybe there is some way to say "ignore the update on this entity" to the persistence manager.
Thats what I mean by tricks ;)