"Staff at a Thailand crocodile farm are nursing an unusual new arrival: a pair of conjoined crocodiles. Chang and Eng - named after the world's most famous Siamese twins - were hatched on Saturday at the Samut Prakarn zoo just south of Bangkok. The animals each have a head, but share a common lower body with one tail and have four legs each."
That picture is from 2001; if they're still alive, they ought to be a lot bigger by now, but I can't find any later mention of them! The Samut Prakarn (or "Samutprakarn"?) croc zoo doesn't seem to have a web page; the only info about it that I've found is on travel agent web sites. (And of course in the news of that woman who commited suicide by crododile there.)
Update: sketchthecow points out that they died of constipation a few months later. "'They died from failure of the digestive system, as they shared a single digestive tract', Samut Prakarn crocodile farm executive director Uthain Yongprapakorn said."