Conjoined twin girls born with the tops of their heads fused together have been separated in a operation at London.Eleven-month-old Rital and Ritag Gaboura were born in Sudan with the tops of their heads stuck together. Twins born joined at the head _ known as craniopagus twins _ occur in about one in 2.5 million births and successful attempts to split them are rare. However, the condition can lead to serious medical problems and the charity said the twins’ parents asked for help funding surgery to pull the two apart. The charity said Sunday the two were finally separated last month and appear to be healthy.