The RadEditor is posting multiple symbols when you select to insert a symbol. This happen when the RenderMode is set to LightWeight. The problem is reproducible also when inserting code snippets via the "Insert Code snippet" tool.
video - http://screencast.com/t/DfBMWrW4Px7I

Steps to reproduce:
1. Open http://demos.telerik.com/aspnet-ajax/editor/examples/rendermodes/defaultcs.aspx
2. Try to insert a symbol through "Insert Symbol" command
    Result: Two symbols are inserted instead of one