title: Generate JSON array with LKJSON in Delphi 7
body: <p>I want to produce something like this: </p>
  
  <pre class="lang-json prettyprint-override"><code>{
    "nrVendas": 2, 
    "totalVendas": 100.0, 
    "vendas": [ 
      {
        "nsuOrigem": "1",
        "data": "2014-03-14",
        "nrParcelas": 1,
        "valor": 50,
        "parcelas": [
          {
            "numero": 1,
            "valor": 50
          }
        ]
      }, 
      {
        "nsuOrigem": "2",
        "data": "2014-03-14",
        "nrParcelas": 1,
        "valor": 50,
        "parcelas": [
          {
            "numero": 1,
            "valor": 50
          }
        ]
      }
    ]
  }
  </code></pre>
  
  <p>I'm trying it this way:</p>
  
  <pre class="lang-pascal prettyprint-override"><code>js3 := TlkJSONobject.Create;
  js3.Add('numero', '1');
  js3.Add('valor', '50');
  
  js32 :=  TlkJSONobject.Create;
  js32.Add('numero', '1');
  js32.Add('valor', '100');
  
  js2 := TlkJSONobject.Create;
  js2.Add('nsuOrigem', '1');
  js2.Add('data', '2014-02-02');
  js2.Add('nrParcelas', 1);
  js2.Add('valor', 50);
  js2.Add('parcelas', js3);
  
  js2.Add('nsuOrigem', '2');
  js2.Add('data', '2014-02-02');
  js2.Add('nrParcelas', 1);
  js2.Add('valor', 50);
  js2.Add('parcelas', js32);
  
  js0 := TlkJSONobject.Create;
  js0.Add('numeroVendas', 2);
  js0.Add('totalVendas', 100.0);
  js0.Add('vendas', js2);
  
  i := 0;
  s := GenerateReadableText(js0, i);
  
  Memo2.Lines.Add(s);
  </code></pre>
  
  <p>But I'm receiving this instead:</p>
  
  <pre class="lang-json prettyprint-override"><code>{
    "numeroVendas": 2,
    "totalVendas": 100,
    "vendas": {
      "nsuOrigem": "1",
      "data": "2014-02-02",
      "nrParcelas": 1,
      "valor": 50,
      "parcelas": {
        "numero": "1",
        "valor": "50"
      },
      "nsuOrigem": "2",
      "data": "2014-02-02",
      "nrParcelas": 1,
      "valor": 50,
      "parcelas": {
        "numero": "1",
        "valor": "100"
      }
    }
  }
  </code></pre>
  
  <p>Then I try to validade this JSON, but i received this error:</p>
  
  <blockquote>
    <p>SyntaxError: Duplicate key 'nsuOrigem' on line 13</p>
  </blockquote>
  
  <p>I think I need to use an array on the fields inside <code>vendas</code>, but I searched in all of the documentation and more, but I can't find anything that can help me.</p>