Is it permissible for two people to give the adhan, one after the other?

Question : There is no harm in two people giving the adhan, one after the other, because the Prophet (peace and blessings be upon him) had Bilal and Ibn Umm Maktum give the adhan for him; when one went down, the other would come up. It is not recommended to have more than that, nor is it recommended.

Answer : Look, there is a point of consideration regarding the hadith of Bilal, where one comes up and the other goes down, and this coming up is subject to consideration. The correct view is that there is a duration between them, because of his statement: "Bilal gives the adhan at night to wake up your sleepers and send back your standers, so eat and drink until you hear the adhan of Ibn Umm Maktum."
If there were only this brief duration between them, he would not have said "to wake up your sleepers and send back your standers," because if the sleeper woke up, what could he accomplish? And if the one standing returned to eat the suhur, what could he accomplish? So the correct view is that there is a duration between them sufficient for the suhur. As for his statement "there is no harm..."
...in two people giving the adhan, one after the other, its apparent meaning is that if they gathered together, there would be harm in it.
Because they say that their gathering together has no benefit. But if it is one after the other, the one who did not hear the first will hear the second.