Cannot redeclare class SourceFileInfo

I try to integrated ImageUploader in my website but I have a problem.

When I test on my local computer with WAMP , it's work.

But when i try on my webserver , it doesn't work...

The Java console return a Fatal Error in PHP

Upload complete. Result page:
<br />
<b>Fatal error</b>:  Cannot redeclare class SourceFileInfo in <b>/********/modules/upload/UploadedFiles.php</b> on line <b>1616</b><br />

EndOf Result page

I have a page with the plugin and another page for process upload.

the first one have an require_once('ImageUploader.class.php');

and the second one have : require_once('UploadedFiles.php');

If you know why the script return this error, help me.

Thx a lot.