Duplicate values in a column when another column has duplicated values

WalterM91 

As variant

let
    Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
    names = Table.ColumnNames( Source ),
    #"Changed Type" = Table.TransformColumnTypes(
        Source,
        {
            {"ID", type text},
            {"Letter", type text},
            {"Value", Int64.Type}
        }),
    #"Grouped Rows" = Table.Group(
        #"Changed Type",
        {"Letter"},
        {
            {"Data",
                each [
                    tblOrder = Table.Sort(_,{{"ID", Order.Ascending}}),
                    fillUp = Table.FillUp(tblOrder,{"ID"}),
                    getRow = Table.FirstN( fillUp, 1 )
                ][getRow]
                 
            }
        }),
    keepData = Table.SelectColumns(#"Grouped Rows",{"Data"}),
    expandData = Table.ExpandTableColumn(
        keepData,
        "Data",
        names, names)
in
    expandData

Please check attached.