Originally posted by thegreenbucket:

how can u tell if a hat is duped....and how is it even possabile is it a hack or mod i dont even know the diff

Go to backpack.tf, write owners steam account url in search section, click on unusual, click history and if it is duped it will show a line that it is duped

is there a rule, that when you sell unusual, and it is duped, you have mention it in trade?