When working with Exercise 3 of the Using ArcMap tutorial, step 4 of the section titled 'Adding a field to an attribute table' returns the error below.
"Failed to add the field to the table/feature class. Cannot create a table with a duplicate column. Field 'POP_DEN' already exists in the table 'tracts'".
There is already a column named POP_DEN in the tracts attribute table.
If you have already completed the 'Joining tables' section of the tutorial and joined the tracts and tract_pop tables, right-click the heading for the tracts.POP_DEN column.