Short answer. Indemnity for damages does arise once, but Article 1224 of the Civil Code does not make every debtor pay equally. Debtors who were ready to fulfill their own promises are not required to contribute to the indemnity beyond their own portion of the price or the value of the service the obligation involves.
What the law says
A joint indivisible obligation gives rise to indemnity for damages from the time anyone of the debtors does not comply with his undertaking.
Civil Code, Article 1224 — Breach of a Joint Indivisible Obligation. Read the full provision →
What the law says
The debtors who may have been ready to fulfill their promises shall not contribute to the indemnity beyond the corresponding portion of the price of the thing or of the value of the service in which the obligation consists.
Civil Code, Article 1224 — Breach of a Joint Indivisible Obligation. Read the full provision →
The breach triggers indemnity for the whole obligation
Article 1224's first sentence is broad: a joint indivisible obligation gives rise to indemnity for damages the moment anyone of the debtors fails to comply. Because the obligation is indivisible, one debtor's non-compliance affects performance of the whole thing, not just their individual slice of it — that is the nature of indivisibility. So the right to indemnity does arise from a single debtor's breach, without needing every debtor to have failed.
But the ready debtors are protected from open-ended liability
The second sentence limits how far that indemnity can reach against debtors who did nothing wrong. A debtor who was ready to fulfill their promise does not contribute to the indemnity beyond the value corresponding to their own portion of the price of the thing, or the value of their own share of the service. In practical terms: the debtor who breached bears the exposure the breach created, while the others are shielded down to what their own share was worth.
So the answer is neither 'all equally' nor 'only the one who breached'
The article's structure means the question "do all of them owe damages" does not have a simple yes-or-no answer. Indemnity for damages exists as a consequence of the breach, involving the group as joint debtors of an indivisible thing, but the amount each ready debtor can actually be made to pay is capped at their own portion's worth — they are not exposed to the full measure of damages the breaching debtor's conduct caused.
Working out the actual numbers
Applying this in practice means first identifying which debtor or debtors actually failed to comply, and then working out what each ready debtor's own portion of the price or service was worth, since that figure is their ceiling. If you are on either side of an indivisible joint obligation where one debtor has defaulted, that calculation — not a simple equal split — is what determines how much each person can be asked to contribute, and it is worth working through with a lawyer.