CKEditor generates different code depending on browser

I'm using CKEditor in our cms application. Using the editor, we want to create HTML code that can be viewed on different browsers. So I think that the code generated by CKEditor should NOT depend on the browser used for working with CKEditor.

Example : when I paste a simple table from excel (2 rows, 2 columns) into CKEditor, the code generated by CKEditor while working with IE8 is

<table border="0" cellpadding="0" cellspacing="0" style="width: 96pt; border-collapse: collapse" width="128" x:str="">
   <colgroup>
      <col span="2" style="width: 48pt" width="64" />
   </colgroup>
   <tbody>
      <tr height="17" style="height: 12.75pt">
         <td class="xl24" height="17" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; width: 48pt; height: 12.75pt; border-top: #d4d0c8; border-right: #d4d0c8" width="64">
            <font face="Arial" size="2">aa</font></td>
         <td class="xl24" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; width: 48pt; border-top: #d4d0c8; border-right: #d4d0c8" width="64">
            <font face="Arial" size="2">bb</font></td>
      </tr>
      <tr height="17" style="height: 12.75pt">
         <td class="xl24" height="17" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; height: 12.75pt; border-top: #d4d0c8; border-right: #d4d0c8">
            <font face="Arial" size="2">cc</font></td>
         <td class="xl24" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8">
            <font face="Arial" size="2">dd</font></td>
      </tr>
   </tbody>
</table>

and the code generated by CKEditor while working with Firefox is

<table border="0" cellpadding="0" cellspacing="0" width="128">
   <col span="2" style="width: 48pt;" width="64" />
   <tbody>
      <tr height="17" style="height: 12.75pt;">
         <td class="xl24" height="17" style="height: 12.75pt; width: 48pt;" width="64">
            aa</td>
         <td class="xl24" style="width: 48pt;" width="64">
            bb</td>
      </tr>
      <tr height="17" style="height: 12.75pt;">
         <td class="xl24" height="17" style="height: 12.75pt;">
            cc</td>
         <td class="xl24">
            dd</td>
      </tr>
   </tbody>
</table>

I think this is a major problem ! How can this be solved ?