Fatal error: Cannot redeclare [plugin]_install()

Hi all,

I was really hoping somebody might be able to help me out with a bug that has had me stumped for afew hours.

My code can be found here: http://wordpress.pastebin.com/m4bcc38d3

And the Exact error message is:
Fatal error: Cannot redeclare microb_install() (previously declared in C:\wamp\www\wordpress\wp-content\plugins\microblogger\microB.php:16) in C:\wamp\www\wordpress\wp-content\plugins\microblogger\microB.php on line 84

Where line 16 is global $wpdb, $wp_roles, $wp_version; and 84 is the final }.

Thanks in advance for any help,
Sam