Gemara

(Beraisa): If one gave (for Pidyon ha'Ben) five Sela'im (in all) to 10 Kohanim at once, he was Yotzei;

If he gave one after the other, he was Yotzei.

Chulin 132b (Rav Chisda): One gives the foreleg to one Kohen, the stomach to a second Kohen, and splits the jaw among two Kohanim.

Question: Rav Yitzchak bar Yosef taught that in Eretz Yisrael, they split every bone among two Kohanim!

Answer: He discusses an ox. Rav Chisda taught about a Seh. (Its limbs are smaller.)

Bava Kama 110a (Rava): (If one stole from a convert and swore falsely, and the convert died, he gives the theft to the Kohanim.) If every Kohen (in the division) does not get a Perutah, he was not Yotzei.

The Torah calls it "Asham that is returned (...to the Kohen)." It must be returned to every Kohen.

Pesachim 32b (Beraisa): If a Zar ate a k'Zayis of Terumah (b'Shogeg), he pays Keren v'Chomesh;

Aba Sha'ul says, he pays only if he ate the value of a Perutah.

The first Tana learns from "v'Ish Ki Yochal Kodesh bi'Shgagah." The Shi'ur of 'Achilah' (eating) is a k'Zayis. Aba Sha'ul's learns from "v'Nosan (la'Kohen Es ha'Kodesh)." The Shi'ur of 'Nesinah' (giving) is a Perutah.

Rishonim

Rambam (Hilchos Bikurim 9:17): One who gives Matanos Kehunah may not give half the stomach or half the foreleg to a Kohen. He must give the entire stomach to a Kohen and the entire foreleg to a Kohen. It says "Titen Lo" - it must be a proper amount for a gift. One may give pieces (of these limbs) of an ox if each is a proper gift.

Rambam (11:7): If one gave five Sela'im even to 10 Kohanim, whether at once or one after the other, he was Yotzei.

Rashi (51b DH b'Zeh): 'At once' is when he put five Sela'im in front of all of them, and went away. 'One after the other' is when he gave to another Kohen. A Tosefta (Bechoros 6:4) says so.

Note: This is like our (and the Maharsha's) text of Rashi. The text according to the Bach and Tzon Kodoshim (and, it seems, all other Meforshim cited in this Halachah) says 'one after the other' is when he gave to one Kohen.' The Tosefta supports this.

Ri Korkus: Rashi says that if he gave to 10 Kohanim one after the other, he was not Yotzei. He supports himself from a Tosefta that says 'if one gave five Sela'im to 10 Kohanim, he was Yotzei. If he gave to him one after the other, he was Yotzei. This connotes he is Yotzei with with one after the other only when he gives to one Kohen. The Rambam follows the simple reading of the Beraisa in the Gemara, which connotes that the Seifa, which discusses giving one after the other, also discusses giving to 10 Kohanim.

R. Yom Tov Algazi (Hilchos Bechoros Sof 8:81, DH v'Hinei Kasav): The Beraisa in the Gemara connotes like the Tosefta. If both laws (at once, and one after the other) both discuss giving to 10 Kohanim, the Tana should have taught them together, i.e. 'if he gave to 10 Kohanim, whether at once or one after the other, he was Yotzei.' Rather, he taught two clauses (i.e. after each, it says 'he was Yotzei') because the Seifa (one after the other) discusses giving to one Kohen. It seems that it depends on whether he intended to finish paying. One after the other helps only when he gives to one Kohen, for then he will finish paying him. Intent to give the rest to other Kohanim does not help (unless he gives to all of them at once), for this is not considered giving at once. The Rambam and Tosfos (48b DH d'Rebbi) say that one is Yotzei also if he gives to 10 one after the other. Perhaps their text of the Beraisa was all one clause. Regarding Machatzis ha'Shekel, the Rambam (Hilchos Shekalim 1:1) says that one must give all of it at once, but not a little today and a little tomorrow. Why is it different than Pidyon ha'Ben? We must say that the Rambam says to give it all at once for the ideal Mitzvah, but b'Di'eved one is Yotzei even if he gave it in halves. If so, also regarding Pidyon ha'Ben l'Chatchilah one must give it at once, like the Beraisa connotes.

Tosfos (Pesachim 32b DH v'Ein): Aba Sha'ul holds that 'Nesinah' is at least a Perutah. Chachamim disagree only because it says 'Achilah'. We hold that one piece of wheat exempts the entire stack (for Terumah), even though it says 'Nesinah'! We acquire with a Kli even though it is worth less than a Perutah, even though it says "he gave to his fellowman." A Get on Isurei Hana'ah is Kosher, even though it says "v'Nasan b'Yadah." We can answer that Nesinah of payment must be a Perutah, like returning theft, which must be at least a Perutah. Other places (that are not payment), even though it says Nesinah, do not require a Perutah. In Kerisus (6b), regarding putting Shemen ha'Mishchah on a Zar, R. Yehudah learns from Terumah to require a k'Zayis. He should be stringent to say that it is any amount, like we find regarding Zerikah, and putting blood and oil on the thumbs and toes of a Metzora, which is like anointing. This is not difficult for the opinion that argues with R. Yehudah and obligates for any amount.

Mazel Sha'ah (cited in Sedei Chemed Ma'areches Nun Klal 21 DH Gam): One may give Pidyon ha'Ben to many Kohanim. If each received less than a Shavah Perutah, what is the law? If we consider the giver, he gave a Shi'ur. If we consider the recipients, they did not receive a Shi'ur.

Sedei Chemed: He had a Safek because Matanos Kehunah must be proper gifts. One may not give half a stomach. Less than a Perutah is nothing. If one gave Gezel ha'Ger to one Kohen, he was not Yotzei. He must give it to the Mishmar. Even so, if everyone gets less than a Shavah Perutah, he was not Yotzei, for this is not called Hashavah (returning). Pidyon ha'Ben may be given to one Kohen, all the more so he was not Yotzei if he gave less than a Shavah Perutah to each Kohen! Really, Matanos Kehunah are different, for "v'Nasan l'Kohen Es ha'Zero'a" connotes an important gift. It does not say Nesinah regarding Pidyon ha'Ben! However, the Minchas Chinuch (392) said 'if one gave less than a Shavah Perutah to each Kohen for Pidyon ha'Ben, this is nothing, like we find in many places.' It seems that he said so from his own reasoning.

Sedei Chemed (DH v'Ra'isi): Ben Yehudah (31) resolved the contradiction in Tosfos the way the Ritva explains why R. Shimon obligates lashes for eating any amount. Through eating it, he showed that it is important. When a great person receives a gift, it is as if he gave, and this can make Kidushin (Kidushin 7a). Tosfos in Pesachim says 'in other places, even though it says Nesinah, a Perutah is not required.' These 'other places' are Terumah and Chalipin. Regarding Terumah, the Torah said "give to him." This shows that it must be considered an important gift regarding the receiver. Since he accepted it, he showed that it is important, it is as if were a Shavah Perutah. The same applies to Chalipin, for it says "he gave to his fellowman." Elsewhere, where the Torah does not attribute to the receiver, Nesinah teaches that one must give a Shavah Perutah. When the recipient is passive, e.g. Ploni put Shemen ha'Mishchah on a Zar (Reuven), Reuven did nothing to show that this is important, so he must put an important amount (to be liable). If so, on Purim, Matanos l'Evyonim must be at least a Perutah, for the verse does not attribute them to the recipient.

Poskim

Shulchan Aruch (YD 61:9): One may not give Matanos to many Kohanim. Each much receive a proper amount. He gives the stomach to one, the foreleg to one, and the jaw to two. One may divide the foreleg of a big ox among two if each is a proper gift.

Shulchan Aruch (307:7): If one gave five Sela'im, even to 10 Kohanim, whether at once or one after the other, he was Yotzei.

Bach (9): Rashi connotes that if he gave to 10 Kohanim one after the other, he was not Yotzei. The Tur holds like the Rambam.

Prishah (11 DH Bein): My Rebbi (the Maharshal) holds that Rashi's Perush is primary.

Chasam Sofer (YD 297, b'Sof): It seems that l'Chatchilah, one may not divide the five Sela'im among two Kohanim. Whenever the Torah gave a Shi'ur, if he divides it this is Chetzi Shi'ur. Even though b'Di'eved he was Yotzei, the ideal Mitzvah is to eat the Shi'ur at once or to give a Shi'ur (to be given) at once.

Pischei Teshuvah (10): How does the Chasam Sofer explain YD 61:9? The only concern is that he gives a proper amount, but he need not give the full Shi'ur to one Kohen!

Chachmas Adam (150:2): One gives the five Sela'im to one Kohen, or even to 10 Kohanim, at once or one after the other. Some say that to one Kohen, one must give at once. Even though the Gemara and Poskim say 'he was Yotzei', which connotes that l'Chatchilah one may not do so, it seems that this is not so. This is like other Matanos Kehunah. See 61:9 (which says that it is proper to give to different Kohanim).