Numbers reconciliation in PowerQuery with M language

let
    Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
    rows = List.Buffer(Table.ToRows(Source)),
    f = (s, c) =>
        [a = s{0},
        match = List.Select(s, (x) => {a{1}, a{2}} = {x{1}, -x{2}}){0}? ?? {},
        upd_c = if List.IsEmpty(match) 
            then c & {a} 
            else c & {a & {match{0}}} & {match & {a{0}}},
        upd_s = List.RemoveMatchingItems(s, {a, match}),
        next = if List.IsEmpty(s) 
            then c
            else @f(upd_s, upd_c)][next],
    upd_rows = f(rows, {}),
    z = Table.FromList(upd_rows, (x) => x, Table.ColumnNames(Source) & {"Linked ID"}, null)
in
    z

Hi, olena2212 AlienSx , dufoq3 

Another solution with Table.Group

let
  Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
  Abs = Table.AddColumn(Source, "Abs", each Number.Abs([Amount])),
  Group = Table.Group(Abs, {"Vendor name", "Abs"},
     {{"Data", (x) => let 
          positive = Table.ToColumns(Table.SelectRows(x, each [Amount]=[Abs])),
          negative = Table.ToColumns(Table.SelectRows(x, each [Amount]=-[Abs])),
          data = Table.FromColumns(positive & {negative{0}}, Table.ColumnNames(Abs) & {"Linked ID"}) &
                 Table.FromColumns(negative & {positive{0}}, Table.ColumnNames(Abs) & {"Linked ID"})
          in data}}),
Result = 
  Table.Sort(
    Table.SelectRows(
      Table.RemoveColumns(
         Table.Combine(Group[Data]),
         {"Abs"}),
      each [Id]<>null),
  {{"Id", Order.Ascending}})
in
Result

Stéphane