Keep in mind Voyager, that full size planes operate in Re range of couple of millions - that's why NACA report 824, a holy bible of NACA profiles, has each of the airfoil tested at Re=3, 6 and 9 million. The results with these figures might will be a bit different, compared to 25k-100k (?) range presented on the site you found (maybe it's the data prepared for RC modellers?).
Well, their polars look somewhat "fishy" anyway. I don't know the software they used for obtaining these, but I'd try to find some alternative source.
Cheers.
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