Hector Duarte Jr. - All Headline News Staff Reporter

On Sunday, Montefiore Medical Center confirms Clarence began walking on his own after "Dateline NBC" showed images of the 3-year-old taking steps at Blythedale Children's Hospital in Valhalla.

Doctors plan to detail the milestone and issue a medical update on the twins at a news conference slated for Monday morning.

Clarence's steps come about a year and a month after the operation at Montefiore in which doctors separated the boys, who were born connected at the tops of their heads. Surgeons cut through a small section of brain they shared.

Before then, Clarence and his brother Carl had been unable to sit up, stand straight or see one another's face.

But they have made great progress in almost every area except speech. Carl is expected to follow in his brother's footsteps soon.

Doctors says the Aug. 4, 2004, separation was like a renaissance for the boys, who were in extreme danger during their infancy in the Philippines. Because they were limited to lying on their backs, their development was stunted and they were prone to chronic pneumonia caused by inhaling food into the lungs.

The boys and their mother, Arlene Aguirre, came to New York in 2003 when Montefiore agreed to take the boys' case for free and Blythedale agreed to donate housing and therapy.