When paragraphs are pasted from e.g., MS Word, multiple BR tags are pasted instead of the corresponding amount needed.

The flowing custom handler shows how this can be handled as per to the specific requirements:

<telerik:RadEditor runat="server" ID="RadEditor1"
    OnClientPasteHtml="OnClientPasteHtml"
    StripFormattingOptions="AllExceptNewLines">
</telerik:RadEditor>

<script type="text/javascript">
    function OnClientPasteHtml(editor, args) {
        var commandName = args.get_commandName();
        var contentToPaste = args.get_value();

        if (commandName === "Paste") {
            contentToPaste = contentToPaste.replace(/(<br\/>)+/gi, "<br/>");

            args.set_value(contentToPaste);
        }
    }
</script>