Filter shows up twice in non grouped columns

[ColinMorris83]

Hey, does anyone have an idea on how to prevent the filter from showing up twice in columns that aren't defined as being part of any group? In my case, I have the first two columns pinned left and they are just defined as standard columns. The others are then all subcolumns of the column with header 'Agent'. However, when showing the filters, it duplicates the filter.