They seem to have disabled the code rather quickly, so I doubt that many orders were completed anyway. Most of the developers would just write it off as "yup, it happened but it's fixed now." Not the first and not the last time when some secret code appears and people jump in without even researching what they're getting, because you need to act fast and create a new account which kinda sounds like a win for the website's traffic. Unless someone hoarded 100 keys and is about to sell those in the second-hand market, then it's a problem for sure. But a few individuals acquiring something they never even considered to get?
I may or may not have checked the rest of their catalogue. I know I did with a few developers that had a price glitch, and I ended up getting extra because I discovered some great stuff just like that. But it's their decision. However, I think it's healthy to sometimes let it slip and see a flock of new users exploring your catalogue. Kontakt libraries are something you can't even demo unless it's some separate demo version, which hardly anyone provides.