<div id="PRIMATABELLA" style="position:absolute; width:300px; height:10px;
z-index:1; left: 50px; top: 50px; border: 0px none #000000">
<TABLE> ecc ecc </TABLE>
</div>

<div id="SECONDATABELLA" style="position:absolute; width:300px; height:10px;
z-index:1; left: 350px; top: 50px; border: 0px none #000000">
<TABLE> ecc ecc </TABLE>
</div>

cosi usando i Layer ?

pao