Create a new column based on distinct result

Hello Anonymous 

try out this solution. It uses Table.Group and depending on your indicated conditions, applies different calculations.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("vZPRSsMwFIZf5dDr0qUZXuzSBS8E2camiIwhYT3dDrRJTNIx38Zn8cnMxSZoI81NpclFkj/w/eTrdpstLR2eFL2tsX5lZZZnYfT2XsIUnfO6RQu3YfH58fcHZc4ZKxgbyP1M3p0NKodQawuikZZq2ktPWoWzZ/JHuHeuw2yXR5DLHnPxcKkyMvW8c6TQOVh11uiAv9AeVlafqMIqgZxHyPmY5OyaXKrmHYTFijwIaSvYNGQmGy89tqg8kANz6VEkFJlGikz/5QkWGh6pRRBHaQ/oBlh5xHD+2/D5MOhNGuj3jdk1v8Y9kvGggigmTRQeU5z3FR8TO/X33H0B", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"ORIGINAL UNIQUE REFERENCE" = _t, #"# (sequence per line item, i.e. 1,2,3) of Inserted Line " = _t, #"NEW UNIQUE REFERENCE" = _t, #"ORIGINAL (Y)" = _t, #"Customer Name" = _t, #" Spend - Expense Amount (USD) " = _t, #" AMOUNT IN QUESTION " = _t, SPECIFIC = _t, #"Current Audit Status" = _t]),
    #"Renamed Columns1" = Table.RenameColumns(Source,{{" Spend - Expense Amount (USD) ", "Spend - Expense Amount (USD)"}}),
    #"Renamed Columns" = Table.RenameColumns(#"Renamed Columns1",{{" AMOUNT IN QUESTION ", "AMOUNT IN QUESTION"}}),
    Trans = Table.TransformColumns(#"Renamed Columns",{{"AMOUNT IN QUESTION", each Number.From(_, "en-US"), Int64.Type}, {"Spend - Expense Amount (USD)", each Number.From(_, "en-US"), Int64.Type}}),
    #"Grouped Rows" = Table.Group(Trans, {"ORIGINAL UNIQUE REFERENCE"}, {{"Custom", (group)=>  if List.Max(group[#"Spend - Expense Amount (USD)"])> List.Sum(group[AMOUNT IN QUESTION]) then  List.Sum(group[AMOUNT IN QUESTION]) else  List.Max(group[#"Spend - Expense Amount (USD)"])  , type number}})
in
    #"Grouped Rows"

Copy paste this code to the advanced editor in a new blank query to see how the solution works.

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Have fun

Jimmy