It'll only work that way if you put the columns in the group as well. Notice, in my image, that Code and name are in a different group to Ptype, which (again) are in a different group to Year. I suspect you are presenting the value of MRN and name outside of the group, and hence why it's repeating. I can't tell that from the non-design view of your report though.
Excuse my typos and sometimes awful grammar. My fingers work faster than my brain does.