Well it is more likely as this:
I have a mt_rand(); in one a file(call it filerandom1.php).
So I set that to a new int as:
$master_username = mt_rand(10000,50000);
How that I need the $master_username in another file(i.e: randomfile22.php) and I need them to be identical in both files. How can I do that? Since when I do the include(), I get all other information on that page. So specific I only need the $master_username's value.