I have a Siamese twins watermelon(s).They are very rare and I don't believe there is a single documented case in the United States. I grow Carolina Cross melons for competition and first noticed the twin ovaries 5 days ago. I hand pollinated it with pollen from a seed from the world record 291 Kent watermelon. You may view this melon and it's progress by viewing my growers diary on bigpumpkins.com

Here is a link that might be useful: Tennessee Dreamers growers diary on bigpumpkins.com