The mishna on 12b days that if someone goes to arei miklat and kills someone there, he has to go to a different neighborhood and a Ben Levi has to go to a different city. My question is regarding both of these cases that why do they have to go to a different neighborhood or a different city but they are both now standing in arei miklat so what's the point of now going to a different arei miklat let them just stay put?
Benzi, London
From Rashi on the Mishnah it appears that someone who kills b'Shogeg is Chayav to be Goleh from wherever he is living at the time, even from an Ir Miklat. It just so happens that someone who is already living in an Ir Miklat because of an earlier Chiyuv Galus is prohibited from leaving the city, and the new Chiyuv Galus is not Docheh the earlier Chiyuv Galus. As a result he is Goleh to another neighborhood in that city. A Ben Levi living in an Ir Miklat does not have this restriction and must be Goleh to another Ir Miklat.
Avraham Phillips
How do you see this from Rashi in the mishna Rashi doesn't really speak it out?
Rashi DH Goleh explains that if someone kills b'Shogeg while residing in an Ir Miklat due to a previous Chiyuv Galus, he isn't permitted to go to a second Ir Miklat. He says "Eino Reshai l'Tzeis". The Chiyuv Galus resulting from the first Retzichah prevents him from being Goleh to another Ir Miklat.
In contrast, in the following Rashi he says that a Levi Rotzeiach b'Shogeg who was already living in an Ir Miklat prior to the Retzichah must go to another Ir Miklat since he is not restricted by a previous Chiyiv Galus. "she'Hu Reshai l'Tzeis me'ha'Ir she'Lo Galah l'Sham". He's not resdiding there due to a prior Chiryuv Galus.
Avraham Phillips
I'm still not really clear because the whole reason why someone has to go to galus is to protect him in order that the goel hadom can't kill him so now that he went and killed in arei miklat let him just remain there why does he have to go to a different neighbourhood I'm not sure what you see from Rashi this is a question on the mishna that why does the mishna have to say Goleh mi'Shechunah l'Shechunah let him just stay in the same Shechunah which he is in now?
Beis Din is Chayav to send a Rotzeiach b'Shogeg to Galus as an Onesh for his crime (Rambam Hilchos Rotzeiach 5:1), and this is the primary reason he is Goleh. The protection provided by the Ir Miklat is a side benefit for the Rotzeiach.
He is Chayav a second Galus if he kills b'Shogeg while he is in an Ir Miklat, but the prior Chiyuv Galus prevents him from being Goleh to a different Ir Miklat. He fulfills the second Galus by being Goleh mi'Shechunah l'Shechunah.
Avraham Phillips