Feature names are case sensitive and duplicates can easily be created, either manually or via CSV import.
With Store Commander, you can quickly tidy up duplicated features by using the 'merge' optio, the icon on the toolar of the Features panel (Catalog menu).
To merge duplicates, select them in the list and hit the merge icon.
The older value (lower ID) will be kept and the other(s) deleted.
All products using the deleted duplicated features will automatically be updated after the merge action.