None of the YM lineages are the same. So, they did get changed.
And it's a bigger (ridiculous) assumption that YM would have had multiple contradictory versions of his MA, than that he just didn't teach everyone fully.
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So is the same true of WSL? Because Dave Petersen differs from Phillip Bayer who differs from Gary Lam who differs greatly from Wan Kam Leung. So in your opinion was WSL as poor a teacher as Ip Man and didn't teach everyone fully?