1. Control Panel > Users
2. Edit firstname.lastname@example.org user
3. Change first name to "X,X" (without the quotes)
4. Click "View All" to return to the front page
5. Click "Export"
6. Open the CSV file and you'll see
There's 3 columns is this entry
The correct output is
which only has 2 columns.
Also affect names with a double quote in it. For example: Mike "The Situation" Sorrentino.
The name is just one example of an affected field. This also affects custom fields as well as any other fields that you can enter in "users.export.csv.fields"