
The condition that it bears is called Polycephaly. It's a birth defect which allows an animal to be born with two heads or the condition to have two heads. Two-headed animals are often found in symbolism and fables but this is a real condition which can be found in many animals, even humans. Seeing a two headed snake in a dream can refer to a love affair or a love triangle. They have been documenting Polycephaly even during the 30's.
Polycephaly is just a really a emphasized example of conjoined twins. These
twins happen only when identical twins don't separate completely. So instead of
the two twins, you end up with twins who are still attached. This description is listed on an earlier post on my blog.
http://www.telegraph.co.uk/news/picturegalleries/picturesoftheday/8878687/Pictures-of-the-day-9-November-2011.html?image=3