I tried to reproduce your issue, but I am not facing such problem. Could you please send me your whole sample project, so I will be able to better assist you?
On a side note, I'd like to inform you that we've just released an online tool that allows you to reduce the size of your Silverlight applications. For more information, please visit http://blogs.telerik.com/blogs/posts/10-06-10/telerik_assembly_minifier.aspx
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