(Mishnah): If a man betrothed a woman and her daughter or a woman and her sister simultaneously, they are not betrothed.

There was once a case of five women, two of which were sisters, and a man collected a basket of Shemita figs from their field and said, "All of you are betrothed to me with this basket''. One of them accepted the basket on behalf of all of them and the Chachamim said that the sisters were not betrothed.

(Gemara - R. Chiya bar Ba): We learn five laws from this case...

Five women can be betrothed simultaneously;

A woman can accept betrothal for herself and for her friend;

One cannot betroth with a stolen item (as the only reason that the betrothal took effect on the other women was because it was Shemita produce and not theirs);

One can betroth with unlawful produce (i.e. of Shemita);

Kidushin does not take effect on any forbidden marriages (that would be punishable with the death penalty or Kares).

R. Elazar: The sisters were not betrothed and if a person separated and sacrificed two sacrifices for one sin, he receives atonement.

Question: What is the case of this latter law?

Answer: If he slaughtered two Chatas sacrifices as one, the altar 'selects' the suitable one but neither may be eaten. If he slaughtered two Asham sacrifices as one, the altar selects the suitable one but neither may be eaten.

R. Zeira citing R. Yochanan: If he slaughtered the first one 'shelo lishmo' (not intending it to be that sacrifice) and the second one 'lishmo' (with the correct intention), he achieves atonement; as the first one is only valid because of the correctly brought sacrifice that followed.

But if he slaughtered the first one with the correct intention and the second one without, although the first one atones, but how can the second one atone! Can it atone for Tumah that occurred between the two sacrifices?! (There was no space of time that Tumah could have occurred.)

But for a Pesach sacrifice, if he brought two simultaneously, he does not fulfil his obligation, because the Pesach sacrifice is brought to permit its meat to be eaten (and one of them is invalid since it was slaughtered without intent for the people designated upon it. Since we do not know which one that is, they are both invalid.)

This does not follow R. Noson, who said that as long as the blood was thrown, even if the meat cannot be eaten, he has fulfilled his obligation.