I got a second opinion before I was dx. My first neuro diagnosed CIS and appeared to be waiting for me to have a relapse before he would dx MS but I had read up on the types of MS and thought PPMS was more likely. I didn’t explicitly ask my GP to refer me for a second opinion but I was saving the first neuro’s feelings.
When I saw my current neuro he started by taking a history - symptoms, when each had developed, how they’d changed, had I had any problems with this or that - thorough, working through a mental checklist to make sure nothing got forgotten. Then he took me into the examination room next to the consulting room and went through various tests of my reflexes and coordination - the same ones the first neuro had done and more. He concluded by saying he wanted me to have an MRI of my brain and spine (previous neuro had only had my brain scanned), plus LP and VEP that the first neuro had not ordered.
Although my neuros are both based in the same hospital, I see them at different hospitals (neuro services at my local hospital are provided by doctors from a different hospital in the area). The impression I got at my first appointment with my current neuro was that he knew I had previously seen one of his colleagues but that he hadn’t looked at the notes - he certainly didn’t have them in front of me, he had that hospital’s file on me. As we went through what tests I’d had and what I’d been told about the results, he was too professional to criticise his colleague but I got a distinct impression that he wasn’t very impressed. He clearly wasn’t going to let anyone else’s thoughts influence him, hence having to have the MRI re-done, but that suited me.