This problem was also addressed in 2010 with no solution at the time.
@Leo suggested to send a feature request asking that DUAL=remember be extended to remember which side things were on. @Abr did sent a request.
I don't know if the option has already been extended in the meantime. If so, I also would like to know how to use it. (I see no options in Help) If not, I also would like to see it added.