[JMBroad]

Get legal advice. My guess would be that the agent which introduced the client initially would get the commission, whereas the second agency should have done their homework and established whether the client had already viewed that property before.

If the client does not want to work with the first agency because he considers them to be unprofessional I'm not sure what happens because effectively they did their job and brought you a buyer.

The situation you described sometimes happens when the buyer tries to get a discount off the sales price. Imagine agency a) told the buyer that the property was worth what you were asking for it, whereas agent b) told them they should haggle. Agency b) then offers the client some of their commission in order to close the sale.

Unless you know what exactly happened, you can't really make a decision.

Good luck though, but find out through your lawyer, and pref. as soon as possible, just in case you are liable to pay the commission twice.

In Spain, if an agency can prove beyond doubt that they were involved in the brokering of the house and if they have a signed contract with the seller to sell the house, they will eventually get their commission by taking the seller to court. However I'm not sure the same applies in Portugal and what happens with double situations like the one you mentioned.