Usually, real estate companies will not list a property unless the person who lists the property owns it or has some other legal right such as a power of attorney to do so. Many contracts of sale contain a provision in which the seller warranties that the seller has marketable title to the property. Read your contract. You shoud also ask the real estate agent outright if the seller has title. It may be that the seller has a lien on the property the seller is trying to remove before the seller can close. There is not enough information in your question to tell but to answer your main question -- yes it is very unusal for a real estate company to list a property that is not owned by the persson listing the property.