I'm getting duplicate entries in my DB

I have some really simple code that takes data from established variables and throws them into the mySQL database. However, sometimes it is processed twice leading to duplication. I can't figure out why this is happening. Any suggestions? Here is the code:

// Enter their comments into the communication table
$date = date("Y-m-d");
$type = "Initial";
mysql_query ("INSERT INTO communication (date, person, email, type, text) VALUES (

'$date',
'$ID',
'$email',
'$type',
'$comments')");

Double-pump on the submit thanks to slow server response, maybe?

I tknow this because I've tested it by carefully clicking the button once. Even when I do it once, sometimes there will still end up being two entries in the db.

Thanks.

Maybe you're including a file twice under certain circumstances or something. I can't really provide any more help unless you paste your whole script in.