In short, no, you can't return twice, the function exits after the first one.
However, this may do what you want:
function two_tables($atts, $content = null) {
return '<div id="table1"><table class="table table-bordered">'.$content.'</table></div>
<div id="table2"><table class="table table-bordered">'.$content.'</table></div>';
}
This is the two outputs combined together.