I believe your brother's condition is called spina bifada occulta which is the least severe form of the conditon and can only be determined through radiologic exams. More severe forms of spina bifada involve greater protrusion of the spinal cord through the back and are visible on physical exam.
Spina bifada occurs due to incomplete closure of the bony encasement of the spinal cord and occurs during prenatal development.
I think that the reference to "two spinal cords" may refer to a splitting of the cord at its distal end and some of the cord has protruded with the majority of the cord in its proper alignment. I have no knowledge of any birth defect that would include two distinct spinal cords, so this would be very unusual if your brother actually has this condition.
Spina bifida occulta usually doesn't cause symptoms or require treatment unless additional problems are occurring as well.
Post again with an update and any additional questions/concerns you may have.
What your brother suffers from is Diastematomyelia or commonly called Split Spinal Cord Malformation (SSCM). In diastematomyelia, or split cord syndrome, an abnormal growth of bony or fibrous tissue forms a spur within the spinal canal, parting longitudinally (not severing) the nerves of the spinal cord, which rejoin into a single tract below the spur. The spinal cord can become tethered at the location of the split.
So your brother has a Tethered Spinal Cord (TCS), caused by the Spina Bifida Occulta and will have to have surgery to un-tether the cord. The longer it goes untreated, the more nerve damage will progress. Once those nerves are damaged, they can not be repaired or regenerate. The surgery to release the cord will Stop further damage to the nerves.
So his best course of action at this point is finding a doctor that has EXPERIENCE treating ADULT TCS. If you would like more info regarding these defects, please don't hesitate to contact me. I have done EXTENSIVE research on all these defects.
As I too was born with SBO and have suffered for over 13 yrs with symptoms of TCS, yet the doctors in my state are NOT educated in the field of Adult TCS, nor have they even heard of it. I have had to become my own advocate and FIGHT to get proper medical treatments. I am still fighting with doctors to get my defect recognized for the debilitating defect that it is. I have nerve damage in my spine and R. leg and I KNOW it is from the SBO, but the doctors don't believe me, yet they can NOT tell me just what is causing it. They believed it could be from Diabetes, but that too was ruled out. The only logical explaination is the birth defect I was born with....but try telling that to a doctor that thinks he wrote the book on SBO/TCS.