Offers on multiple properties

[Nick Scalero]

I'm looking for the correct verbage to add to a contract where I am making offers on multiple properties but once one of the offers has been accepted all the other offers are no longer in effect. Something like, "The buyer may submit purchase offers on multiple properties. This offer to purchase becomes invalid if one of the buyers other offers is accepted. Any deposits submitted with this offer will be returned to the buyer at this time."

Is this legal? Anyone else do this?