(Mishnah): Those who may not marry a regular Jew may marry each other.

R. Yehudah: It is forbidden.

R. Eliezer: A vadai (definite) may marry a vadai but a vadai with a safek (doubtful) or a safek with a vadai or a safek with a safek is forbidden.

These are the cases of safek - A shtuki, an asufi or a kusi.

(Gemara R. Yirmiyah): A Yisrael with a cut organ may marry a Mamzeres.

R. Yosi: When the Mishnah permitted those who may not marry a regular Jew to marry each other, this only applies to one who has a disqualification because of his lineage, but if he has a disqualification in his own body, he may not marry another Jew who was disqualified from marrying a regular Jew.

Support for R. Yosi (R. Chilkiyah/ R. Simon citing R. Yehoshua ben Levi) - They only taught (that a man with a cut organ may marry a convert) if he is a Yisrael, but if he is a Kohen, he may not. Just as you say there that a definite Kohen may not marry a convert, so too a definite Yisrael may not marry a Mamzeres.

(In the Mishnah, R. Yehudah ruled that a Mamzer may not marry a Mamzeres.) R. Imi said that R. Yaakov Gevulaya taught before R. Yochanan/ R. Yitzchak bar Tavlaya citing R. Shimon ben Lakish - R. Yehudah ruled this way so that a Mamzer would not be able to marry and Mamzerim would vanish from the world (rather than produce offspring).

Question: (According to R. Yehudah who prohibits a convert from marrying a Mamzeres, meaning that he holds that the congregation of converts is considered part of the regular congregation) does he therefore also rule that an Amoni cannot marry a Amonis?

R. Yosi bei R. Bun: According to the reason given by the Rabbis (Raish Lakish and R. Yochanan above (h)), is there any question (it is certainly permitted)?! As if R. Yehudah holds that converts are disqualified from marrying in the congregation, an Amoni cannot marry an Amonis since she is part of the congregation; he cannot marry a Mitzris, as he is called the congregation compared to her!

Solution (R. Matanya): An Amoni may free his slave woman and then marry her.

Question: Does R. Yehudah also say that a Mitzri may not marry a Mitzris?

Proof (Beraisa -R. Abahu to R. Yochanan): R. Yehudah says - Binyamin the Mitzri convert was a student of R. Akiva. He said, "I am a Mitzri convert married to a Mitzris convert. My son is the son of a Mitzri convert and I will marry him off to a Mitzris convert thereby making my grandson able to marry a regular Jewess.'' R. Akiva said to him, "No, my son, marry him off to the daughter of a Mitzris convert in order that their child will be third generation on both sides.''