bug report for sitemap

My programer got the following error on installing sitemap and seo...
thank you for your help.
Olivier

- sitemaps-and-seo-wordpress-mu-style-1.0.3
After the installation reported:
Fatal error: Cannot redeclare class all_in_one_seo_pack in /home/unecerta/public_html/wp-content/plugins/sitemaps-and-seo-wordpress-mu-style-1.0.3/all_in_one_seo_pack.php on line 477
[not installed]