It seems there is a problem with one of the registrations -- the version should match the Telerik.Web.UI.dll version. Alternatively, you can remove the Culture, Version and PublicKeyToken or even remove both registrations altogether and use the VisualStudio smart tag as shown in #4 here
If you still encounter problems, it would be best that you open a formal support ticket and send a sample project that reproduces the problem so that we can investigate further.
the Telerik team
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