How to remove duplicates according to a field and obtain the internal code of the document

Solve the problem: from the open list (possibly a list with multiple lines), re-obtain the internal code of the document;

/// <summary>
/// menu click event, the form plugin is also applicable
/// </summary>
/ // <param name="e"></param>
public override void BarItemClick(BarItemClickEventArgs e)
{
switch (e.BarItemKey)
{
//case "TBDELETE": list toolbar button event, through button Key[uppercase] Distinguish which button event
case "tbDelete"://Delete button, execute to delete the corresponding member coupon information (member file);
if (this.ListView.SelectedRowsInfo.Count > 0)
{
List<string> dstr = new List<string >();
ListSelectedRowCollection dstr4 = this.ListView.SelectedRowsInfo;
IEnumerable<string> dstr5 = dstr4.GetPrimaryKeyValues().ToArray().Distinct();
foreach (string dstr2 in dstr5.Distinct())
{ BillCommon.Delmemq(this .Context, dstr2); }
}
else
{ this.View.ShowMessage("No row data is selected!"); }
break;
default:
break;
}
}