Due to Facebook limitations, it is only possible to add one BookNow button to each Facebook fan page. This is because of how Facebook processes the BookNow application. Within any Facebook fan page, you can only have one application installed of the same type, which means you cannot install multiple instances of the BookNow application.
If you have multiple properties and want to have a BookNow application for each property, we suggest that you create a unique Facebook fan page for each unique property. That way, you will be able to add the BookNow application to each of your property's Facebook fan pages.