Not the only boxer, sir. Leo Houck also fought from flyweight to heavyweight. http://boxrec.com/media/index.php/Leo_Houck
The Alvarez Clan(Canelo's brothers) hold the record for most brothers fighting on the same card with 7.
I wonder how "accurate" those facts are. I assume they only include fights covered by compubox or something? So they basically ignore fights from outside of the US...
A recent female fight did it too...can't remember the names but it was 140 and...147 titles I think Hyun Mi Choi won a "big 4" world title on debut (only fighter to do so) A Japanese fighter (male) has never a world title in Europe Bill Squires Vs Tommy Burns was the first trilogy for the World Heavyweight title...Squires was the first man to come up short in 3 world title shots to the same champion
Wladimir Klitschko, in his fight against Alexander Povetkin, initiated more clinches than punches thrown. He also set a new CompuClinch record, which was previously held by John Ruiz.