Why does it say “a convert who converts,” wouldn’t it be more correct by saying “a gentile who converts”? He is not a convert until he actually converts.
Margaliyos HaShas quotes from a sefer: At the time that the entire Jewish Nation was standing by Har Sinai to receive the Torah, the souls of all the future proselytes were there, as well. Some converted immediately and others took a long time, but they were all there.
This is the explanation: A convert, one whose soul was present by Har Sinai when the Jewish people received the Torah, and is now converting, is regarded as a newborn baby.
[Interesting readings relevant to converts:
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