[villasluz]

Hi there,

first of all you must be sure that you didn`t give to one (or both - by error) of the agents the exclusivity rights.
If you gave the exclusivity to one of them, than you will have to pay the one who has exclusivity, as he is the only agent who has the right to promote your property...independent of the fact through which agent the buyer desires to buy.

If none of them has the exclusivity, in this case the buyer has the right to choose with whom he wants to buy the property and this will be the agent that you will have to pay.
There is a type of "law" which says: "The clients are always the kings..."
In this case the client desires to purchase your property through the second agent...so that is what will happen and that is the agent who will receive the commission.

We are real estate agents based in the Silver Coast, Eastern Algarve and Central Algarve, so I know what I am speaking about.

Good luck
Antonio