Replace Index Match with VBA - Multiple Criteria - Thousands of rows and columns

Hi,
If your data starts in A1 and it is a header (same for each sheet) then replace

         For i = 1 To UBound(ar, 1)

with

         For i = 2 To UBound(ar, 1)

As you found out, you can not have duplicate keys in a dictionary. So you need to exclude the header from the compilation by starting in row 2.