Troitzky's line is about which positions can be won at all, not won within 50 moves. There are many winning positions in this ending where the best line takes more than 50 moves.
2knightsking vs pawnking endgame
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But look at this position, conditions are ok but my tablebases show that with best play mate is done in 60 moves! And i am asking, why is that, 2nd trotsky line is wrong?