How do I filter by multiple Smart Map addresses?
You would need to setup two criteria models, one for each Smart Map field, and query for the element IDs. Merge these IDs and have a 3rd criteria model where you pass in the IDs to the id parameter.

See this question for example code:  


  Complex logic on a ElementCriteriaModel parameter?


Here's a blog post describing the technique in details:


  Manipulating Craft's ElementCriteriaModel objects with Twig


If you need better performance, have a look at the custom Yii query builder code I posted here:  


  How can I query for entries that have one of two Lightswitch fields enabled?