Short answer. The contract with the earlier date takes priority. When a principal and agent each contract with different persons for the same thing and the two contracts are incompatible, the Civil Code gives preference to the one executed first — subject to the rules on double sale for immovable property.
What the law says
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 →
The basic rule: earlier contract wins
Article 1916 of the Civil Code addresses the specific situation where both a principal and his agent — acting independently — each enter a contract with a different person regarding the same property, and the two contracts cannot both be honored. The rule is that that of prior date shall be preferred. Whether it was your contract as principal or your agent's contract that came first, the earlier one takes effect. The later one, being incompatible, cannot co-exist with it and must yield. This is the default priority rule for this type of conflict.
What the double sale rules add
Article 1916 adds an important qualification: its priority rule applies without prejudice to the provisions of article 1544. Article 1544 governs the situation where the same property is sold to two different people. For immovable property, the buyer who in good faith first recorded the sale in the Registry of Property takes ownership — even if the other buyer contracted earlier. For movable property, the one who in good faith first took possession wins. The interplay means that the date of the contract matters, but registration and good faith possession can override it for certain types of property.
Good faith and registration are decisive for land
If the property at stake is land, what ultimately matters most is which buyer registered first — provided that buyer acted in good faith at the time of registration. A buyer who knew about the earlier contract cannot hide behind earlier registration; bad faith defeats the registration priority. So while Article 1916 starts with contract date as the tiebreaker, for immovable property the final answer under Article 1544 depends on registration in good faith. The buyer who runs to the registry first, without knowledge of the competing claim, tends to prevail even over an earlier contract.
What this means for you as principal
If your agent entered a contract before yours did, the buyer your agent dealt with likely has a prior claim — and if that buyer also registered in good faith, the advantage is compounded. If your contract came first, you are in a stronger position on the date priority, but you still need to consider whether the other buyer has already registered or taken possession. Either way, the existence of two incompatible contracts is a legal dispute that will need to be resolved through court proceedings. The buyer whose contract is displaced will likely have a separate claim for damages against whoever is responsible for the conflict.