Short answer. As a starting rule, the earlier of the two contracts is preferred. But that is only the starting point: where the thing is land or another immovable, the double-sale rule decides ownership by good-faith registration, so a later buyer who registered first in good faith can still prevail.
What the law says
When two persons contract with regard to the same thing, one of them with the agent and the other with the principal, and the two contracts are incompatible with each other, that of prior date shall be preferred, without prejudice to the provisions of article 1544.
Civil Code, Article 1916 — Incompatible Contracts With Agent and Principal. Read the full provision →
What the law says
Should it be immovable property, the ownership shall belong to the person acquiring it who in good faith first recorded it in the Registry of Property.
Civil Code, Article 1544 — Double Sale. Read the full provision →
How this usually happens
It is normally an accident rather than a scandal. You ask a relative or a broker to find a buyer, then find one yourself, and neither of you knows the other has closed. Article 1916 covers exactly that: When two persons contract with regard to the same thing, one of them with the agent and the other with the principal, and the two contracts are incompatible with each other, that of prior date shall be preferred, without prejudice to the provisions of article 1544. Both buyers may be entirely innocent. The article is not asking who behaved badly; it is deciding which of two honest contracts prevails.
Prior in date — the general rule
The starting point is the calendar. Where the two contracts cannot stand together — the same vehicle, the same lot, sold twice — the earlier one is preferred. Dates therefore matter enormously, which is why a buyer should insist on a dated and signed document rather than a handshake and a receipt written up later. It also follows that the buyer who loses the thing is not left without recourse against the person who dealt with him. Losing the property and losing your money are separate questions: a displaced buyer can pursue the seller for what he paid and for what the failed sale cost him.
The double-sale rule can change the answer
The closing words matter as much as the rule itself. Article 1916 applies without prejudice to the provisions of article 1544, which uses a different test. For movable property, ownership passes to the person who may have first taken possession thereof in good faith. For land and other immovables, the ownership shall belong to the person acquiring it who in good faith first recorded it in the Registry of Property. A later buyer who registers first, honestly, can therefore defeat an earlier one who did not register. Good faith runs through every branch of that provision, and knowledge of the earlier sale destroys it.
What to do about it
A buyer of land should check the title before paying and register promptly, because delay is what turns a valid purchase into a losing one. A seller who has appointed an agent should tell him the moment he starts negotiating directly, and should set the limits of the authority in writing if he intends to keep selling on his own. Where two buyers are already claiming the same thing, the dispute is usually settled in court, and the seller or agent in the middle may face claims from the losing side. These cases turn on dates and documents, so take advice early and preserve both.
Related provisions
- Civil Code, Article 1916 — Incompatible Contracts With Agent and Principal
- Civil Code, Article 1544 — Double Sale