פירוש על עבודה זרה 13:6

Joseph responds that this is not a case of two tractates. Nezikin (Bava Kamma, Metzia and Batra) is one tractate, that later in its development was divided into three.
Alternatively, he could justify his opinion by saying that the anonymous opinion in this case has more authority because it was quoted among “legal and fixed decisions.” These are a set of rules that are taught in a pithy and apodictic manner. These mishnayot are not the typical case law—they are rules.