[Plugin: Simple Facebook Connect] Cannot redeclare class Facebook

Why am I getting this error:
<strong>Fatal error</strong>: Cannot redeclare class Facebook in <strong>/***/wp-content/plugins/simple-facebook-connect/facebook-platform/facebook.php</strong> on line <strong>37</strong>
?

I have no other facebook related plugins, I also grepped the plugins directory for any other occurrence of “class Facebook” but found none other than the one in SFC. By the way this happened after I entered FB app details in the plugin settings.

Thanks for any help.