Nothing which you probably don't already know. I recall that the rhyming nickname fashion may have begun in England and Scotland sometime around the end of the 12th century to the beginning of the 13th century, gaining in popularity right up and through Shakespeare's time, and practiced mainly by the lower classes. And, besides "Bob", another rhyming nickname for Robert was "Dob" or "Hob" (from which surnames such as Dobbins and Hobbes were derived). And, of course, there was "Dick" for Richard, "Ned" for Edward, "Peg" for "Meg" or "Margaret", etc.
I dunno how interesting that is. Why is this radio station so interested in the names Bob and Bill, anyway? Is the station manager's name Bob or Bill? :)