[Avodah] Apparently conflicting Stam Mishna

[Looking ForInspiration]

Hello!

This is my first post to aishdas.org, so forgive me and direct me
if needed.

Up until the end of the 4th Perek of Baba Kama, Stam Mishna holds that
when there is doubt, Hamotzi Mechavero Olov Horaayah. In the 5th Perek,
it holds that when in doubt, you divide the money in doubt. Does this
mean that Shisha Sidrei Mishna does not have just one author?

I have done some quick research through the Hakdamas Hamishna Larambam,
Klallei Hamishna, and some other sources, but nevertheless, if someone
can direct me to sources and research on as much detail as possible
as to *what transpired in the process of the Mishna being written* it
would be much appreciated. Did Rebbi write all the Mishnayos (and if so,
the question above is a strong one)? Did Rebbi write some, but in Baba
Kamah he stopped at the 4th Perek, and someone else wrote the rest of
Baba Kama? Did Rebbi or the other authors of the Mishna, if any, write
the Mishna from memory, or compiled previously written text, or both?

Thank you in advance.

Mordechai