Dear Rabbi Kornfeld:
Is there any significance to the change, on daf 26a, from the first lashon to the ika d'amri, to quoting the halacha of kol mar'eh vere'ach ein bahem mishum meilah as "deTanya" rather than as a memra of amoraim?
Gershon
It is possible that the first Lashon of the Gemara did not recognize that this had the status of a Beraisa, as even Rebbi Yehoshua Ben Levi himself is in fact a borderline Tana/Amora (although he is cited in the last Mishnah in Mishnayos, some say it was inserted afterwards). This indicates that Rebbi Shimon Ben Pazi would most likely have the status of an Amora.
We do find arguments, even among the bordeline Tanaim themselves, regarding who was an Amora and who was a Tana (see Tosfos in Kesuvos 8a, DH "Rav" who says that Rebbi Yochanan did not recognize Rav's status as a Tana).
All the best,
Yaakov Montrose