Thank you for writing.
A possible way to achieve the desired appearance is to use our Html-like formatting functionality: http://www.telerik.com/help/winforms/tpf-html-like-text-formatting.html
Attached you can find a sample application demonstrating how to do that. Please note that in my sample I have a semicolon (";") between the dates, which I am using to separate them.
I hope that you find this information useful. Let me know if I can be of further assistance.
the Telerik team