Index duplicates are on hand if two different entries contain two identical values. Index duplicates can come about e.g. due to errors when entering the index values.
Index duplicates are case-insensitive. An index duplicate is thus on hand if two index values differ in uppercase/lowercase spelling only (e.g. “ISO_1234” and “iso_1234”).
Index duplicates can be recognized by the arrow icons and next to the respective index value. The arrow icon indicates that there is an index duplicate for this index value. By clicking the arrow icon, you can go to the entry containing the index duplicate.