Uma forma poderia ser:
<?php
$nowFormat = date('Y-m-d H:i:s');
$sql = "INSERT INTO table SET field='$nowFormat'";
$sql2 = "INSERT INTO table SET field='$nowFormat'";
...
<?php
$nowFormat = date('Y-m-d H:i:s');
$sql = "INSERT INTO table SET field='$nowFormat'";
$sql2 = "INSERT INTO table SET field='$nowFormat'";
...