Clone Detective is a Visual Studio 2008 integrated tool that allows you to analyze C# projects for source code that is duplicated, which can lead to inconsistencies. You can download the setup or the code source from the CodePlex site : Clone Detective for Visual Studio.
It uses the Continuous Quality Assessment Toolkit - the result of several research projects carried out by the Competence Center Software Maintenance & Systems Engineering Group at the Technische Universität München.