ecco qui , la annidi in una tabella con distanza tra celle ="0"

codice:
<table border="1" width="100%" cellpadding="0" cellspacing="0">
  <tr>
    <td width="50%">
      <table border="0" width="100%" cellspacing="0" cellpadding="0">
        <tr>
          <td width="100%">tabella 1</td>
        </tr>
        <tr>
          <td width="100%">tabella 1</td>
        </tr>
        <tr>
          <td width="100%">tabella 1</td>
        </tr>
      </table>
    </td>
    <td width="50%">
      <table border="0" width="100%" cellspacing="0" cellpadding="0">
        <tr>
          <td width="100%">tabella 2</td>
        </tr>
        <tr>
          <td width="100%">tabella 2</td>
        </tr>
        <tr>
          <td width="100%">tabella 2</td>
        </tr>
      </table>
    </td>
  </tr>
</table>