With the "RadControls for Silverlight-4.2010-1-0430" Internal Release we introduced a new functionality of RadUpload -the Batch Upload . Now one upload request (i.e. one chunk) can contain multiple files. As a result the speed of uploading a set of small files is significantly increased. We could not achieve this without introducing some changes in the RadUploadHasndler control. More information about the these changes you can find here
However, I am not sure what RadUpload functionality the project you downloaded illustrates. If you can send us a link to the project, we will update it accordingly and further investigate these issues.
Also, you can examine the examples in our KB articles here
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