question with the preprocessed dataset

[yangarbiter]

Hi,

I have some question about the adult dataset.
https://raw.githubusercontent.com/ustunb/risk-slim/master/examples/data/adult_data.csv

For the first row of data (except the header row), we see that the second and fourth features are 1.
The second and fourth features corresponds to Age_leq_21 and Age_30_to_44.
How is it possible that a person is both below 21 and between 30 and 44?
Is there a mistake in the header row?

Thanks.