Asp finding the same control in 2 DLLs

The
type 'Telerik.Web.UI.RadFormDecorator' exists in both
'c:\WINDOWS\assembly\GAC_MSIL\Telerik.Web.UI\2008.1.515.20__121fae78165ba3d4\Telerik.Web.UI.dll'
and
'c:\WINDOWS\assembly\GAC_MSIL\Telerik.Web.UI\2008.3.1125.20__121fae78165ba3d4\Telerik.Web.UI.dll'
 My web.config explicity states to use the  3.1125 version in all references...
 Any ideas?  I've tried blowing away the asp.net cache...

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