Filtering operations are registered twice in the undo stack of the ImageEditor.

1. Open http://demos.telerik.com/aspnet-ajax/imageeditor/examples/toolbarmodes/defaultcs.aspx

2. Click on the More arrow on the right most on the Toolbar

3. Click to expand the Brightness/Contrast split button and choose Greyscale

Result: The Greyscale command is added twice in the undo stack of the control