Twice.
I "invented" a unique shape, a prince-shaped bowl (styled after an old Ashton prince, which I've been told was in turn styled after an older Dunhill prince), mated to a long, oval Canadian shank. Over the past 25 years, I've commissioned variations of the Canadian Prince from Paul Bonaquisti and Bill Boyle, I've always meant to have more carvers interpret the shape, but I've not gotten around to it. I don't require all that many pipes, and - while I enjoy the shape greatly - the two examples that I have are more than suitable.
I much appreciate Peterson's shape XL11, which appears throughout Peterson's various lines, including as "The Original" in the Sherlock Holmes series. I had first encountered a Sherlock Holmes Original at a tobacconist, but it's price was out of my range at the time. The first affordable one I found, was a well-used Irish Seconds version. Years later, I picked up a Sherlock Holmes version and, subsequently, gave away the Irish Seconds. One was enough, but I'm very happy with the one I have.