There is not any effect due to using same class. pls use below html
<div id="div1" class="DivHistoFrozen" >
<table class="Labels" border="1" style="width: 95%;" cellpadding="0" cellspacing="1">
<tr><td> </td></tr>
</table>
</div>
<div id="div2" class="DivHistoFrozen" >
<table class="Labels" border="1" style="width: 95%;" cellpadding="0" cellspacing="1">
<tr><td> </td></tr>
</table>
</div>