clone a selectpicker

Good afternoon friends I have the following problem I need to clone a multiple selectpicker which I have in a DOM with an incremetable form that is inside an html table, the problem is that when I add another row the selectpicker appears twice, one that works and another clone that does not work, what I want is that when I give more, for another row, then selectpicker let me select and not clone the first row already registered

      <td><label>Descripción</label>
      <input type="text" name="descripcion[]"  class="form-control" placeholder="Descripcion de la Actividad"/></textarea></td>


      <td><label>R. Ejecución</label>
      <br/>
      <select class="selectpicker"  name="usuario[]" data-actions-box="true" data-live-search="true" data-live-search-placeholder="Search" multiple="">
      <option>

      <option></option>


      <?php
      $query = "SELECT * FROM usuario ORDER BY nombre ASC";
      $registros=mysql_query($query,$conexion) or die("Problemas en el select:".mysql_error());
      while($row = mysql_fetch_array($registros)){
      $usuario=$row['usuario'];
      $nombre=$row['nombre'];


      ?>
      <option value="<?php echo $usuario;?>"><?php echo $nombre;?></option>

      <?php }?>

      </select>
      </td>



      <td>

      <div class="col-md-16">
      <label for="exampleInputEmail1">Fecha Inicio:</label>
      <div class='input-group date' id='datetimepicker5'>
      <input type="text" name="fecha_inicio[]" size="12"  class="form-control" />
      <span class="input-group-addon">
      <span class="glyphicon glyphicon-calendar"></span>
      </span>
      </div>
      </div>
      <!--
      <div class="col-xs-5">   
      <label for="exampleInputEmail1">Fecha Fin:</label>
      <div class='input-group date' id='datetimepicker2'>
      <input type="text" name="fecha_final[]"  class="form-control" />
      <span class="input-group-addon">
      <span class="glyphicon glyphicon-calendar"></span>
      </span>
      </div>
      </div>
      </td>
      -->

      <input type="hidden" name="fecha_final[]" value="<?php echo date("j-n-Y") ?>">

      <td class="eliminar"><p></p><input class="btn btn-danger" type="button" value="Menos -"/></td>

      </tr>



      </table>
      <div class="btn-der">

      <button id="adicional" name="adicional" type="button" class="btn btn-info"> Más + </button>

  

This would be the Javascript code where I generated the clone of the form that is inside the html table where I have the problem with the selectpicker

<script>

      $(function(){

      // Clona la fila oculta que tiene los campos base, y la agrega al final de la tabla
      clon = $("#tabla");
      tr = $('tr:first', clon);
      $("#adicional").on('click', function(){
      tr.clone().appendTo(clon).find(':text').val('');
      clon.find(".date").datetimepicker();
      clon.find('select').selectpicker();




      });
      // Evento que selecciona la fila y la elimina 
      $(document).on("click",".eliminar",function(){
      var parent = $(this).parents().get(0);
      $(parent).remove();
      });





      });
      </script>