Sorry for having you listed as Brandy, the webteam are checking this now.
As per your fix, I'm glad this worked for you. Deleting the key of the ToolBoxControlsInstaller package is not recommended though, as Visual Studio could stop displaying the standard Toolbox Items.
This registry key "tells" Visual Studio to use the package, handling the Toolbox item registration. If it does not exist, the addition of new toolbox items through the registry would fail (i.e. the tools of the component vendors such as Telerik won't get updated automatically).
To my regret the occurrence of multiple Toolbox items is a problem we haven't been able to detect and fix so far, hence I don't have another suggestion.
Just for analysis information: does a Toolbox Reset work fine on your environment with the key deleted? I mean, do you get all the standard and the Telerik tools?
the Telerik team
Let us know about your Windows Phone 7 application built with RadControls and we will help you promote it. Learn more>>