I understand the problem that you have. You can disable the double-click functionality using custom styles. Basically, you need to remove the command, associated with the LeftDoubleClick gesture in the ItemControlStyle, SelectionRangeStyle, SelectionThumbHandleStyle, SelectionThumbHandleStyle Styles. I have attached a project, demonstrating the changes. Please note that I used NoXaml DLLs for the project.
the Telerik team