Match Columns While Making Space for Dupicates

eightbitannotations 

With Power Query in attached file. Query1:

let
    Source = Table.NestedJoin(
        Table1, {"LIST1"},
        Table2, {"LIST2"},
        "MERGED_2",
        JoinKind.LeftOuter
    ),
    AddedList2 = Table.AddColumn(Source, "LIST2", each
        List.Combine( Table.ToColumns([MERGED_2]) ),
        List.Type
    ),
    RemovedMergedTable = Table.RemoveColumns(AddedList2, {"MERGED_2"}),
    ExpandedList2 = Table.AddColumn(RemovedMergedTable, "EXPANDED2", each
        if List.IsEmpty([LIST2]) then {null} else [LIST2],
        List.Type
    ),
    RemovedList2 = Table.RemoveColumns(ExpandedList2, {"LIST2"}),
    ExpandedList1 = Table.AddColumn(RemovedList2, "EXPANDED1", each
        if List.IsEmpty([EXPANDED2])
        then {[LIST1]}
        else {[LIST1]} & List.Repeat({null}, List.Count([EXPANDED2]) -1),
        List.Type
    ),
    RemovedList1 = Table.RemoveColumns(ExpandedList1, {"LIST1"}),
    ListsToTable = Table.FromColumns(
        List.Combine(
            {
                { List.Combine(RemovedList1[EXPANDED1]) },
                { List.Combine(RemovedList1[EXPANDED2]) }
            }
        ),
        {"LIST1", "LIST2"}
    )
in
    ListsToTable