title: yii2 select widget - multiple select in same form
body: <p>I need to use the multiple yii2 Select widget in the same form.
  For each students i need to show the select widget to select the course. 
  When i use multiple select widget in same form only one is appearing
  How to do that?</p>
  
  <pre><code>$form-&gt;field($model, 'course')-&gt;widget(Select2::classname(), [
           'data' =&gt; ArrayHelper::map(course::find()-&gt;asArray()-&gt;where(['isActive' =&gt; '1'])-&gt;all(), 'id', 'name'),
           'options' =&gt; ['placeholder' =&gt; 'Select a course...'],
           'pluginOptions' =&gt; ['allowClear' =&gt; true],
                ]);
  </code></pre>