That's because you're fetching the array outside the loop. It should be:
for($i=0;$i < count($myrow);$i++) {
$myrow = mysql_fetch_array($sql);
$myrow2 = mysql_fetch_array($sql2);
print "<TR>";
print "<TD>".$myrow[$i]. " " . $myrow2[$i] . "</TD><TD>".$myrow[($i+17)]. " " . $myrow2[$i+17] . "</TD>
";
print "</TR>";
}
Also, instead of two queries, you could have done this:
$sql = mysql_query("SELECT no, item FROM vet.$id2 ORDER BY no",$db);
Diego