The idea of getting two biopsies is stupid. Not needed for something that rarely occurs. I doubt seriously that this idea is going to become a standard of care. Two surgical procedures are not needed. There will always be human error. But two biopsies are not needed. Maybe a better system of checking and rechecking to make more sure the specimen is labled and processed correctly.
That probably means her boss was overworking her.
I'd also guess the laboratory budget contains "cost savings" and "productivity" bonuses for the supervisors, which are great incentives to cut corners.
It's basic greed and cheapness, and now some low-level worker gets blamed for it.