title: Validate repeated value of specific column
body: <p>I´m creating Zip file like:</p>
  
  <pre><code>var consultaGerente = _contexto.PDFGenerados.Where(x =&gt; x.nGerente == Gerente).ToList();
  using (ZipFile fileZip = new ZipFile())
  {
      foreach (var i in consultaGerente)
      {
          var fileRoute = carpetaCorrecta + i.vRutaArchivo.Replace("/", "\\");
          zip.AddFile(fileRoute, "PDF");
      }
  }
  </code></pre>
  
  <p>Problem is when  <code>i.vRutaArchivo</code>  is repeated it throws an error because  we can´t add two files with same name to zip . How can I validate <code>i.vRutaArchivo</code> never comes repeated?</p>