Responsa for Yevamot 201:6

ואם היו שניהם במשמר כו': מאי שנא שני משמרות דלא דאזיל להא משמרה ומדחו ליה ואזיל להא משמרה ומדחו ליה משמר אחד נמי אזיל להאי בית אב ומדחו ליה

— R. Aha b. Hanina in the name of Abaye in the name of R. Assi in the name of R. Johanan replied: In order [to avert any possible] reflection on his family.<span class="x" onmousemove="('comment',' Should he abstain from the Temple service, rumour might attribute his abstention to some serious disqualification which would bring discredit upon all his family. Its members, therefore, may compel him to join in the service. ');">¹⁷</span> IF, HOWEVER, BOTH SERVED IN THE SAME MISHMAR etc. In what respect do two mishmaroth<span class="x" onmousemove="('comment',' Plur. of mishmar. ');">¹⁸</span> differ [from one] that [in the former case] he should not [receive a share]? [Is it] because when he comes to the one mishmar he is driven away and when he comes to the other mishmar he is again driven away?<span class="x" onmousemove="('comment',' Each mishmar asserting that he does not belong to them. ');">¹⁹</span> Then, even in the case of one mishmar also, when he comes to one beth ab<span class="x" onmousemove="('comment',' V. Glos. A mishmar consisted of six families each of which was described as beth ab, performing service on a different day in the week. ');">²⁰</span>

Teshuvot Maharam