common character position

blazko 

Try this.

Please see attached file's Query Editor as well for steps

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("dcpBCoNADIXhu8xaQhJnxmSttIuK4FLEhbjoBXoAT+PBPEknhYKKs3vv5xtHt8wfcoUL9VPRx8fw+p993QDcVJyJxKYLt4RTRSZEmkXTBrCdyBGo/ABxDoRo8a1yB8oUhepeGLE1YBsA2iNQi8RlFpBFlSoLKosx+AuYvg==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [Column1 = _t, Column2 = _t, Column3 = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Column1", type text}, {"Column2", type text}, {"Column3", type text}}),
    #"Grouped Rows" = Table.Group(#"Changed Type", {"Column1"}, {{"ALL", each _[Column2], type list}}),
    #"Added Custom2" = Table.AddColumn(#"Grouped Rows", "Custom.2", each Text.Combine(Table.AddColumn(Table.FromColumns(List.Transform([ALL],each Text.ToList(_))),"Result",each 
let mylist=List.Distinct(Record.ToList(_)),
mycount=List.Count(mylist)
in
if mycount=1 then Text.Combine(mylist) else "."
)[Result])),
    #"Expanded ALL" = Table.ExpandListColumn(#"Added Custom2", "ALL")
in
    #"Expanded ALL"