Offer accepted?

Once upon a time, a buyer viewed a condo unit. He liked it and quickly went on to negotiate the price. After some back and forth, the buyer agreed to precisely the seller's asking price–Php50 Mn. So, he prepared the earnest money check.

For some reason, the seller was delaying the acceptance of the earnest money check. Weeks passed, and the seller still refused to receive the payment. The buyer got turned off and withdrew from his offer.

Months later, the buyer found out that the seller delayed receiving the earnest money because he had already accepted a previous offer–for Php40 Mn; and he was trying to get out of it. The seller had accepted an earnest money check for the Php40 Mn offer and attempted to return it.

The Php40 Mn buyer insisted that their deal push through–and it did. It's good that the seller had delicadeza and respected the original agreement–even if it meant losing Php10 Mn.

Lesson?

I've seen contracts that penalize the seller should they back out of the deal (i.e., the seller returns the earnest money plus pay an extra amount to the buyer). The problem with this clause is, how do you determine whether it is the seller's fault the deal doesn't push through? Or, how would you know if he backed out because he went with another buyer?

A probable solution to this predicament is to warn the seller that if he decides to cancel the deal unreasonably, you will put a lien on the property (using the signed offer letter). The annotation would surely scare off other buyers.