Heres an article on the finding of the USS Perch by divers on the MV Empress near Java.
http://starbulletin.com/2007/01/21/news/story07.html
By the amount of wrecks these guys find i dont think you would have to do the same one twice on a trip and all the ones you do could be virgins. Just shows all the hard effort pays off in the end.
Matt
