Power Query Append Queries overwrites data

Yesterday I implemented a workaround (rename the two Customer Code columns so they would not be appended but create two different columns for each source in the result table. Then merge them as one column).

Somehow today it seems to be working fine even without the workaround... No explanation why, I did not change anything. This is my code anyway

let
  Quelle = SapBusinessWarehouse.Cubes("xxxxxx", "xxx", "xxx", [Implementation="2.0"]),
  #"$INFOCUBE" = Quelle{[Name = "$INFOCUBE"]}[Data],
  #"$/ERP/SFIN_V01" = #"$INFOCUBE"{[Id = "$/ERP/SFIN_V01"]}[Data],
  
  #"Hinzugefügte Elemente" = Cube.Transform(#"$/ERP/SFIN_V01",
        {
            {Cube.AddAndExpandDimensionColumn, "[/ERP/CUSTOMER]", {"[/ERP/CUSTOMER].[LEVEL01]"}, {"Customer.Customer Level 01"}},
            {Table.AddColumn, "Customer.Customer Level 01.Key", each Cube.AttributeMemberProperty([Customer.Customer Level 01], "[2/ERP/CUSTOMER]")},
            {Table.AddColumn, "Customer.Customer Level 01.Country (Key)", each Cube.AttributeMemberProperty([Customer.Customer Level 01], "[2/ERP/COUNTRY]")},
            {Table.AddColumn, "Customer.Customer Level 01.City (Key)", each Cube.AttributeMemberProperty([Customer.Customer Level 01], "[2CITY]")},
            {Table.AddColumn, "Customer.Customer Level 01.SalesRep (Key)", each Cube.AttributeMemberProperty([Customer.Customer Level 01], "[2/SFX/ZZ1_Z2SF0]")},
            {Table.AddColumn, "Customer.Customer Level 01.ZIP (Key)", each Cube.AttributeMemberProperty([Customer.Customer Level 01], "[2ZIPCODE]")}
            
        }),
    #"Umbenannte Spalten" = Table.RenameColumns(
    #"Hinzugefügte Elemente",
    {
      {"Customer.Customer Level 01", "Customer"},
      {"Customer.Customer Level 01.Key", "Customer Code"},
      {"Customer.Customer Level 01.Country (Key)", "Country Code"},
      {"Customer.Customer Level 01.ZIP (Key)", "Postal Code"},
      {"Customer.Customer Level 01.City (Key)", "City"},
      {"Customer.Customer Level 01.SalesRep (Key)", "Sales Rep Code"}
    }
  ),
  #"Added Custom1" = Table.AddColumn(#"Umbenannte Spalten", "Customer Level 1 Code", each ""),
  #"Added Custom2" = Table.AddColumn(#"Added Custom1", "Customer Level 1", each ""),
  #"Reordered Columns" = Table.ReorderColumns(#"Added Custom2",
    {
      "Customer Code",
      "Customer",
      "Customer Level 1 Code",
      "Customer Level 1",
      "Postal Code",
      "City",
      "Sales Rep Code",
      "Country Code"
    }
  ),
    #"Appended Query" = Table.Combine({#"Reordered Columns", #"HIST Dim Customer (2)"}),
    #"Added Custom" = Table.AddColumn(#"Appended Query", "Postal Code 2", each Text.Start([Postal Code],2)),
    #"Removed Duplicates" = Table.Distinct(#"Added Custom", {"Customer Code"})
in
    #"Removed Duplicates"