I once made an error of the same sort. I have been measuring a local race for many years. On my second measurement of the marathon course my second measurement differed from my first by about 50 meters. The discrepancy jumped out at me. I had used a fire hydrant as a reference point on the first measurement, and after considerable digging I discovered that I had used the wrong hydrant, 50 meters away, as the reference point on the second measurement. I was able to correct the error.
If I'd made the same error twice, I'd have had a short course. True, in 50 meters nobody would have noticed but the error would have been there. I was happy that I found it in time.
It's a shame that the calibration constant was not seen as being off-normal. This should have raised a flag, but it evidently didn't.
I feel bad for everybody concerned.
Sooner or later, if you measure enough, you are bound to err. It's part of being human.