If accepted, the new version or publication crystallizes a fleeting moment in the tradition and, in so doing, makes further commentaries possible. It depends on the authority of the writer if his composition is to be considered a step forward in the tradition. If we consider a piece of tradition literature like the Mishnah, the situation is similar but not precisely the same. For we can imagine various attempts to publish Mishnayot, orally or in writing, to canonize a particular school’s tradition. That is, in my view, the main reason for the differences between the Mishnayot of the corpus of the Mishnah, the Tosefta and the Halakhic Midrashim, as well as the Mishnayot presupposed in Yerushalmi and Bavli. However, we have to be careful because ancient and medieval manuscript composers and writers could have had different “quotations” of the Mishnah before them, and the successive copyists could have harmonized their quotations according to the “vulgate”, namely according to the commonly used text in the academies.
Giuseppe Veltri, “From The Best Text To The Pragmatic Edition: On Editing Rabbinic Texts”, in The New Testament and Rabbinic Literature, eds. Reimund Bieringer, Florentino García Martínez, Didier Pollefeyt, Peter Tomson (Leiden & Boston: Brill, 2010), 68-69.