Re: Who "ratted" and wht?
I believe the challenging bit with the engines is engineering them so that they separate in a controlled fashion at the right time (and not before!), properly enter their retrieval orientation and deploy chute(s) in good order. Since such hasn't been done before with the new engines being developed, it's not really being paid multiple times for the same work. Time will tell if they have to re-engineer the retrieval hooks or not. I imagine the mass is different, as is the moment arm and center of gravity and the like.
But that would involve actual engineering.