I'm surprised that .bomb won't just stick back-to-back on the same PNR two separate fares (e.g. SYD-(LAX/SFO)-IAD and IAD-ACC), and sum up the costs of the two. (It seems like something beyond that is happening based on the cost.)

I mean, if people could book a FD on a PNR, why not two non-combinable fares back-to-back?

I take it there's more than just an IT limitation in play?