Yes, there was some ongoing maintenance of this code where both versions had to be updated. The original author was not a pilot and was unfamiliar with some of the nuances of FAA airspace. One of the reasons they brought me in was that I am a pilot and knew how the FAA's data should be interpreted.
In the end, not a huge deal, but it was annoying when I had to make the same changes in two places.
While they were wrong in this case, I would say it was a reasonable move to not DRY based on the code pattern itself at the time. And that's the big difference imo - DRYing based strictly on the structure of code vs business processes.
That's not what people want to hear - they want a silver bullet; a set of criteria for which DRY'ing could be determined from the onset!
Was that necessarily a bad thing and something that must be corrected for that code base?
I usually follow the same rule of thumb until I find myself repeatedly updating both at the same time. If I can't update one without updating the other then they must be the same thing and its time to DRY.
Don't Repeat Yourself when updating code.