Gemara

8a (Ula): Mid'Oraisa, a creditor collects Ziburis. "You will stand outside, and the borrower will give to you a security (from his house)." Surely, the borrower will give a low quality security!

(Rava): If one made his slave an Apotiki and sold him, a creditor collects the slave. If he made his ox an Apotiki and sold it, a creditor does not collect it.

This is because people hear about making a slave an Apotiki, but not about making an ox an Apotiki.

33b (Beraisa): If a Tam damaged, after Beis Din judged the case, if creditors collected it, whether the damager borrowed before or after the damage, the collection is invalid, for a Tam only pays from itself.

Question: Even if he borrowed after the damage, since the creditor grabbed the ox first, he should collect from it!

Suggestion: This teaches that if a creditor collected before earlier creditors (and there is not enough to pay them all), his collection is invalid!

Rejection (and answer): No. If a creditor collected before earlier creditors, his collection stands. A damaging ox is different. The damagee says, even if you consider that the ox was yours from when you lent him, I collect it.

Kesuvos 95a (Mishnah): If a man was married to two women and sold his field, and his first wife wrote to the buyer 'I have no claim against you.' The second wife may collect the field from the buyer, the first wife collects from the second, and the buyer from the first wife. This cycle continues ad infinitum, until they reach a compromise. The same applies to a creditor, and to a woman who is a creditor.

Erchin 7b (Rav Ada bar Ahavah): If Reuven had five Shekalim, and he said "Erki Alai", and again said "Erki Alai", if he gave four Shekalim for the latter Erech and one for the former, he was Yotzei for both.

This is because all his money is Meshu'abad (there is a lien on it) to (pay for) the first Erech. It is as if he had no money for the latter (his Heseg Yad evaluation was one Shekel). B'Di'eved, the money he gave for the latter Erech is valid, just like a creditor who collected before earlier creditors of the same borrower.

Rishonim

Rif (Kesuvos 53a): Collection of Metaltelim (out of order) is valid, for it has no Kol. Rava taught that if one made his ox an Apotiki and sold it, a creditor does not collect it, for it has no Kol.

Ran (42b DH Nosan): Nowadays that we collect from Metaltelim or orphans, whoever collected keeps it. There is precedence in Metaltelim only if he was Meshabed them Agav (along with) land.

Question (Tosfos Kesuvos 90a DH Shema): Why do we say that if a later creditor collected, he keeps it? He should be no better than a buyer. An (earlier) creditor can take from a buyer!

Answer (Tosfos): Indeed, Chachamim made a later creditor better than a buyer. This is an enactment, lest people be dissuaded from lending. Even though the earlier creditor loses, people will not be dissuaded, for one can collect first.

Question (Tosfos): What he paid for the latter Erech is valid, just like a later creditor who collected. There, we need not enact lest lenders be dissuaded!

Answer (Tosfos): When both creditors are Hekdesh, there is no concern. Alternatively, in Metaltelim, what was collected out of order is valid.

Question (Rosh Kesuvos 10:11): We say (95a) that the first takes from the second. This shows that collection out of order is invalid, unlike in Erchin!

Answer (Rosh): When both creditors are Hekdesh, there is no concern. Alternatively, there is precedence regarding Metaltelim. We inferred (Bava Kama 33b) that collection out of order is invalid from collection of an ox, even though it is Metaltelim. This is because it is like land, for people call it a gorer. Also, it is proper that the damagee collect it, for he cannot collect from anything else. Normally, collection of Metaltelim stands.

Rambam (Hilchos Malveh 20:2): There is no precedence in Metaltelim. Whoever collected it first keeps it, even if he was the last creditor.

Poskim

Shulchan Aruch (CM 104:1): If Reuven owed many people, the document with the earliest Kinyan collects first, from land or Metaltelim. This is even if another loan was due to be paid earlier. This applies to collecting from Reuven or from one who bought his land.

Beis Yosef (DH Kosav bi'Teshuvos): The (Rashba, in Teshuvah attributed to the) Ramban (61) says that if one was not Meshabed Metaltelim Agav land, if a later a creditor collected Metaltelim, we take it. If creditors come together to collect Metaltelim, we give to the first, for Shibud mid'Oraisa. There is precedence when the borrower has his Metaltelim. There is no precedence regarding buyers, or if a later creditor collected them.

Question (SMA 1): There is no precedence among Metaltelim! The Beis Yosef brought a Teshuvah that there is precedence when they come to collect, but all Poskim disagree. Even the Ramban did not say so l'Halachah; it was a mere reasoning. Do not say that the Shulchan Aruch discusses when he was Meshabed Metaltelim Agav land. He does not discuss this until Sa'if 5! Also, the Rema says that the first creditor cannot take it from him! Also, the Shulchan Aruch says that this is even from buyers. One does not take Metaltelim from buyers, even if they were Meshubad through Agav!

Answer (SMA): The end of this Halachah discusses only land. The Reisha teaches that Shibud mid'Oraisa, therefore mid'Oraisa there is precedence even for Metaltelim. This is relevant even nowadays (after the enactment not to collect Metaltelim from buyers); a later creditor whose debt was due first has no precedence. Also, there is precedence if he was Meshabed Metaltelim Agav land. The Ir Shushan explained the Shulchan Aruch like the Ramban, that there is precedence before they collect. This is wrong.

Gra (2): Tosfos, and the Rif (53a) say that regarding Metaltelim, what was collected was collected. This implies that l'Chatchilah, the earlier loan has precedence, like the Ramban. See Rashi (Erchin Sof 7b, who proves so from Erchin). However, the Rosh says that there is no precedence, like the Shulchan Aruch in Sa'if 10; the Rif on 45a connotes similarly. It seems that there is precedence, like the Shulchan Aruch says here. All Poskim compare a creditor to a buyer. (There is precedence even among Metaltelim; however, if we do not take from a buyer or a later creditor, for there is no Kol.)

Rema: If a later creditor comes to collect land, we help him collect. An earlier creditor can protest that we not collect Metaltelim for a later creditor, lest he sell or destroy them. Further, if a latter creditor collects them, an earlier creditor cannot take them afterwards.

Shulchan Aruch (10): If creditors come to collect Metaltelim, in which there is no precedence, we split the property among them.