From the definition of 相撲部屋 from 三省堂
すもうべや[相撲部屋]⦅名⦆
〘すもう〙年寄(としより)が経営する、それぞれの集団ごとに所属する、力士の組織。部屋。
I am not sure if それぞれ is redundant since ごとに is already used. Is it an example of 重複表現? I am still struggling to grasp the nuances of ごとに but based on my understanding of this definition, 集団ごとに divides all sumo wrestlers into groups (or teams?). Each group have its own unique 相撲部屋 (or 力士の組織), right?