title: Duplicate property/value output callbacks in Dash using clientside_callback
body: <p>It's well established that Dash does not (at this time) allow the same ID/value pair to be resident in two separate callback outputs.</p>
  <p>I'm looking to attempt to mildly circumvent this utilizing a clientside_callback and some javascript that will manually modify a dropdown element in the client.</p>
  <p>A basic example:</p>
  <pre><code>app.clientside_callback(
      &quot;&quot;&quot;
      function(fileName, contents) {
          let element = document.getElementById(&quot;some-component-id&quot;);
          element.options[3].selected = true;
          //Optionally trigger a change event
          element.dispatchEvent(new Event('change'))
  
          return fileName;
      }
      &quot;&quot;&quot;,
      Output('loaded-file',         'children'),
      Input(&quot;some-input-component-1&quot;,      &quot;filename&quot;),
      Input(&quot;some-input-component-2&quot;,      &quot;contents&quot;),
      prevent_initial_call=True)
  </code></pre>
  <p>Now it should be obvious that this isn't working since I'm here posting the question. I've attempted to use other &quot;flavors&quot; of accessing and editing the dropdown to no avail (.selectedIndex = someInt or straight .value = someNewValue.</p>
  <p>Is this an allowed action first of all? Is there something I'm missing about modifying things client-side. I'm quite new to javascript and web development.</p>