Click option in select and open other fields - AngularJS

JavaScript
3

When you load the page in select “Regime” only without value is selected

<select class="form-control ng-pristine ng-valid ng-empty ng-touched" ng-model="icms.regime" ng-options="r.regime for r in data track by r.id">
      <option value="" class="" selected="selected">Selecione o Regime</option>
       <option label="Tributação Normal" value="0">Tributação Normal</option>
       <option label="Simples Nacional" value="1">Simples Nacional</option>
</select>

After clicking on the other two options are all with selected attribute

<select class="form-control ng-valid ng-touched ng-not-empty ng-dirty ng-valid-parse" ng-model="icms.regime" ng-options="r.regime for r in data track by r.id">
        <option value="" class="" selected="selected">Selecione o Regime</option>
        <option label="Tributação Normal" value="0" selected="selected">Tributação Normal</option>
        <option label="Simples Nacional" value="1" selected="selected">Simples Nacional</option>
</select>

I do not know why it happens