title: JSON Schema Validation Duplicate Key Elements
body: <p>My Schema;</p>
  
  <pre><code>{
  "title": "Reporting Schema",
  "type": "object", 
  "properties":  {    
     "id" : {"type": "string", "minLength": 1, "maxLength":25 },
     "firstName" : {"type": "string", "minLength": 0, "maxLength":25 },
     "middleName" : {"type": "string", "minLength": 0, "maxLength":25 },
     "lastName" : {"type": "string", "minLength": 0, "maxLength":25 },
     "companyName" : {"type": "string", "minLength": 0, "maxLength":70 },
     "address1" : {"type": "string", "minLength": 0, "maxLength":50 },
     "address2" : {"type": "string", "minLength": 0, "maxLength":50 },
     "city" : {"type": "string", "minLength": 0, "maxLength":20 },
     "state" : {"type": "string", "minLength": 0, "maxLength":2 }
  },
  "required": [ "id"],
  "additionalProperties": false
  }
  </code></pre>
  
  <p>My data to test; You can see it has multiple firstName Values.</p>
  
  <pre><code>{
  "id" : "SchemaTest",
  
  "firstName" : "D",
  "firstName" : "D",
  "firstName" : "D",
  
  "middleName" : "M",
  "lastName" : "Bro",
  "companyName" : "",
  "address1" : "Test_Address_One",
  "address2" : "Test_Address_Two",
  "city" : "City_Name",
  "state" : "US"
  }
  </code></pre>
  
  <p>Is it possible to have my schema validate that the data isn't matching the schema contract and have it flag a false validation?</p>
  
  <p>I'm thinking there might be an option in the <em>addtionalProperties</em> section.</p>