[Closed] Don't add duplicates to a dotnet listview – help please

Hi all

I have a button that when pressed, allows the user to select files from explorer and then the result is displayed in a dotnet listview. When the button is pressed again, more files can be added to the list.

So this works great:

theRange = #() 
for x=1 to lvItems.count do ( li = dotNetObject "System.Windows.Forms.ListViewItem" lvItems[x]; append theRange li )  
lv.Items.AddRange theRange

BUT, I don’t want any duplicates, so if I replace

append theRange li

with

appendifunique theRange li

it doesnt work. It still adds duplicates to the list if the user selects the same files. What am I doing wrong?