Custom layout groupings for BI Report

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I've created a learning plan completion report with a custom layout. In the custom layout, I have it grouped by last name. When I run the report, there are two individuals who have the same last name. Only one of the individuals appears on the report, but with duplicate values for the training. I'm assuming it's pulling both training records into the one account. So it shows one individual with one learning plan but then duplicated mapped items within that learning plan.
 
I can't figure out how to adjust my custom layout so that it groups by last name and then by first name (which I'm assuming is what I need to do to fix the issue).