So obviously, even those very experienced with snakes can make mistakes on gender.Snakes are full of mysteries & surprises- maybe that's why we love them so much?
BTW, did you candle the larger, white egg? Sometimes they don't color up right away. It's funny that your RBB waited until "quite mature" to pull this stunt, much like the very mature rosy boa did with me, many years back. It really does seem to be nature's "Hail Mary pass" to save their species & of course with RBB, it really took years for her to fully recover anyway, before attempting "single parenthood".
I hope you're still in touch with your vet tech friend- I'd love to see his expression now too.Not to mention that it's a real credit that he was able to save this snake when she was so badly injured in the first place. Pretty amazing.