JSFiddle - React, Tailwind, and code Playground

HTML

<table id="test" border="1">
    <tr>
        <td>test1</td>
        <td>test2</td>
        <td>test3</td>
    </tr>
      <tr>
          <td>test4</td>
          <td>test2</td>
          <td>test5</td>
    </tr>
    <tr>
        <td>test6</td>
        <td>test2</td>
        <td>test9</td>
    </tr>
          <tr>
              <td>test6</td>
              <td>test8</td>
              <td>test8</td>
    </tr>
    <tr>
              <td>test6</td>
              <td>test8</td>
              <td>test5</td>
    </tr>
</table>

JavaScript

var seen = {};
$('#test td').each(function() {
    // Encode column and content information.
    var index =  $(this).index();
    var txt = $(this).text();
    if (seen[index] === txt) {
        $(this).text('');
    }
    else {
        seen[index] = txt;
    }
});