TStringList.Duplicates

property Duplicates: TDuplicates Access mode: RW

Description
describes what to do in case a duplicate value is added to the list:
 * dupIgnore: Duplicate values will not be be added to the list, but no exception will be triggered.
 * dupError: If an attempt is made to add a duplicate value to the list, an exception occurs.
 * dupAccept: Duplicate values can be added to the list.

If the stringlist is not, the Duplicates setting is ignored.