There are two Final Grade columns in the current version of ICON: one for the Calculated Final Grade and one for the Adjusted Final Grade. The difference between the two Final Grade columns is that the Calculated Final Graded strictly calculates the final grade, while the Adjusted Final Grade allows the instructor to manually adjust the Final Grade (i.e. manually bumping a student up from 89.95% to 90%).
To change the column names in the gradebook, click Manage Grades, then click one of the "Final Grade" links and edit the name.