Quite a few of these deformed, or as some called them, 'Siamese twin' frogs have been spotted lately Jo although I don't think anyone is actually sure of just what exactly causes such a phenomenon.

Does anyone have any theories? If you could manage to get a photograph for us it would be much appreciated.

Here's a report I found that you may be interested in.
3 Headed Frog Found
Frog Also Has 6 Legs
March 5th. 2004.
Wildlife experts in Britain are stunned by the apparent discovery of a frog with three croaking heads and six legs, Local 6 News will report Friday night.
The frog was reportedly found at a children's day nursery in the English village of Weston Super-Mare in Somerset, according to the report.
The staff at the Green Umbrella nursery first thought it was three frogs huddled together but after closer inspection they realized the frogs were joined together.
A wildlife biologist said a reason for the three-headed frog’s development could have been damage to the embryo, according to a report.
Others say the malformations are caused by GM crop experimentation, pesticides, changes in the environment or even virus's attacking the eggs.