1899,
Yes, s/n for many of the years in both of those are indeed wrong, as are all works that are based on Madis' work. For all the great work he did (Madis is / was a legend in the Winchester world) some of his work was inaccurate. For the Model 1894 and the 1892, his early production numbers are high and then drop behind actual production. For almost all of the other models, his numbers are behind. I am unsure, as are most, as to how this happened. For example, I have a 38-55 which Madis dates to 1906, while the PRRs at Cody puts it at 1908. However, it is the opposite for later 2 1894s I own: I have an 1894 s/n 876902 which Madis dates to 1920 and which the PRR show actually dates to 1918, and another, s/n 933115 which Madis dates to 1923, though records show it was made in 1921.
If you're interested in more on this topic, check out the WACA forum, it's been discussed ad naueum there. Not a lot of people outside of the Winchester collecting world are aware of this discrepancy, but the good folks at Cody are trying to get the word out.
Cheers,
Matt