Combine recursive listing with excluded code

[Paul_Hossler]

LMGTFY

https://en.wikipedia.org/wiki/Hash_function

A hash function is any function that can be used to map data of arbitrary size to fixed-size values. The values returned by a hash function are called hash values, hash codes, digests, or simply hashes. The values are usually used to index a fixed-size table called a hash table. Use of a hash function to index a hash table is called hashing or scatter storage addressing.

I had a Hash module that I added to the attachment.
The test data in the attachment (your folder tree) was order randomized
The MarkDupsWithHash sub was run to mark dups in red
The data was resorted as a check

Option Explicit


Sub MarkDupsWithHash()
    Dim r As Range
    Dim aryHash() As String
    Dim i As Long, j As Long
    
    'test
    Worksheets("Files").Columns(1).Interior.ColorIndex = xlColorIndexNone
    
    
    Set r = Worksheets("Files").Cells(1, 1)
    Set r = Range(r, r.End(xlDown))


    ReDim aryHash(1 To r.Rows.Count)


    For i = LBound(aryHash) To UBound(aryHash)
        aryHash(i) = CreateSHA256HashString(r.Cells(i, 1).Value)
    Next i


    For i = LBound(aryHash) To UBound(aryHash) - 1
        For j = i + 1 To UBound(aryHash)
            If aryHash(j) = aryHash(i) Then r.Cells(j, 1).Interior.Color = vbRed
        Next j
    Next i


    MsgBox "Done"


End Sub

If you don't want to use a Hash, then the For i / For j loops should also work, but will be slower I think