Add code below the select list to return it to the first row like:
<select name="size_<?php echo $RepeatSelectionCounter_1; ?>">
<?php do { ?>
<option value="<?php echo $row_rsSizes['SizeID']; ?>"><?php echo $row_rsSizes['SizeName']; ?></option>
<?php } while ($row_rsSizes = mysql_fetch_assoc($rsSizes)); ?>
</select>
<?php
mysql_data_seek($rsSizes, 0);
$row_rsSizes = mysql_fetch_assoc($rsSizes);
?>