If you often work with 2 tables together, you might wish to display them side-by side instead, as shown below.

<!doctype html public "-//W3C//DTD html 4.0 //en">
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
    <title>Suppliers And Shippers</title>
    </head>
<body>
    <iframe
        frameborder="0"
        width="49%" height="600" align="left"
        src="suppliers_view.php"></iframe>
    <iframe
        frameborder="0"
        width="49%" height="600"
        src="shippers_view.php"></iframe>
    </body>
</html>