DAX Identifying Duplicated Values

Hi,

This M code works fine

let
    Source = Excel.CurrentWorkbook(){[Name="Data"]}[Content],
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Meter Point", Int64.Type}, {"Filter", type text}, {"Invoice_End", type date}}),
    #"Added Custom" = Table.AddColumn(#"Changed Type", "Custom", each Number.ToText([Meter Point])&[Filter]&Date.ToText([Invoice_End])),
    Partition = Table.Group(#"Added Custom", {"Custom"}, {{"Partition", each Table.AddIndexColumn(_, "Index",1,1), type table}}),
    #"Expanded Partition" = Table.ExpandTableColumn(Partition, "Partition", {"Meter Point", "Filter", "Invoice_End", "Index"}, {"Meter Point", "Filter", "Invoice_End", "Index"}),
    #"Removed Columns" = Table.RemoveColumns(#"Expanded Partition",{"Custom"}),
    #"Added Custom1" = Table.AddColumn(#"Removed Columns", "Dup", each if [Index] = 2 then "Dup" else null),
    #"Removed Columns1" = Table.RemoveColumns(#"Added Custom1",{"Index"}),
    #"Changed Type with Locale" = Table.TransformColumnTypes(#"Removed Columns1", {{"Invoice_End", type date}}, "en-IN")
in
    #"Changed Type with Locale"

Hope this helps.