let
Source = Excel.CurrentWorkbook(){[Name="stock1"]}[Content],
AjtStock2 = Table.Combine({Source, stock2}),
GroupBy = Table.Group(AjtStock2, {"Art_Code", "Dos_Code"}, {{"Total STOCK 1", each List.Sum([Total STOCK 1]), type nullable number}, {"Total STOCK 2", each List.Sum([Total STOCK 2]), type nullable number}, {"Eacrt", each List.Sum({List.Max([Total STOCK 1]),-List.Max([Total STOCK 2])}), type nullable number}})
in
GroupBy