Nested Tables duplicated rows through JSON

It's quite logical that each expansion of a column with nested tables will create additional rows, so the other columns will be duplicated the same number of times; also the other columns with nested tables.

There is a way to combine the nested tables, as illustrated in the query below.

However, I wonder how your query looks like so far.

It looks rather strange to me that you arrived in the situation with the nested tables.

Maybe you can share your query with some fake data?

Query CombinedTables:

let
    Source = 
        #table(
            type table[LeadId = Value.Type(Table1), First Name = Value.Type(Table2), Created Time = Value.Type(Table3)],
            {{Table1,Table2,Table3}}),

    #"Added Custom" =
        Table.AddColumn(
            Source, 
            "CombinedTables", 
            each Table.FromColumns(
                Table.ToColumns(
                    [LeadId])&
                Table.ToColumns(
                    [First Name])&
                Table.ToColumns([Created Time]), 
                Value.Type([LeadId]&[First Name]&[Created Time])), 
            Value.Type(Source[LeadId]{0}&Source[First Name]{0}&Source[Created Time]{0})),

    #"Removed Other Columns" = 
        Table.SelectColumns(
            #"Added Custom",
            {"CombinedTables"}),

    #"Expanded CombinedTables" = 
        Table.ExpandTableColumn(
            #"Removed Other Columns", 
            "CombinedTables",
            {"LeadID", "First Name", "Created Time"},
            {"LeadID", "First Name", "Created Time"})
in
    #"Expanded CombinedTables"

The 3 tables and my queries: