VB.Net - Hashset allows duplicates

Hi Experts.   Can some one please explain why my hashset allows duplicates.  If I test the contents of the folder and the hashset, they are the same but I know there are duplicates.  I thought hashsets did not allow duplicates
        Dim files = Directory.EnumerateFiles(Path, "*.*", SearchOption.AllDirectories)
        Dim myHashSet1 As New HashSet(Of String)
            For Each f In files
                If (myHashSet1.Add(f)) Then
                    'do nothing
                    'do something
                End If
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Fernando SotoRetiredCommented:
If you have two or more files with the same names but in different directories then they are NOT the same and therefore will not cause a issue to add them to the HashSet. And because you can not have two files in the same directory with the same name I think this is what is happening.

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AndyAinscowFreelance programmer / ConsultantCommented:
>>If I test the contents of the folder and the hashset, they are the same but I know there are duplicates.

How do you test for duplicates?
What is, in your opinion, a duplicate?  (Two files, one an exact copy of the other: a.txt and copy of a.txt - duplicate, to the user yes, to the hashset no.)
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Visual Basic.NET

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