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In Lesson 2 it states that the Dhatukatha was regarded by the orthodoxy as apocryphal, referencing commentary on the Samyutta Nikaya

In Lesson 3 it states that the Kathavatthu was regarded by the orthodoxy as apocryphal, also referencing the same commentary, though a different section

If both of these statements are accurate, how did there exist an orthodox Abhidhammapitaka in six books (as rejected by the Mahasangikas)?

Were there different groups within the orthodoxy that held one or the other as apocryphal?

Lesson 4 hints at this by stating that not all of the Theravada schools accepted the text as canonical

If the disagreement was within the Theravada schools, how do both of the above statements exist within the same commentary?

Thanks in advance!