Yes, if you have cancer then you have cancer but cancer symptoms are often similar to other illnesses and with cancer there is something tangible to see on the x-rays/scans; there is nothing tangible to see about X or personality disorders, just symptoms.

I would ask your new Dr. and nurse to ask him why he changed it and/or see if it is not just a mistaken identity; maybe the Dr. was in a rush and thought you were someone else when he wrote it; presumably there would be notes he took somewhere in your files?

But if your new Dr. and nurse are working with you the way you like and agree with you on what is wrong, etc. then I wouldn't worry about whether or not the other is there or not?