Which row will keep Table.Distinct(Table, {"Column"})

Hey v-lid-msft , I did a quick test and that does not seem to be the case.

First, I entered the data from that example

and used 'Remove duplicates' on b

This is what we expected from the documentation and from the assumption that it keeps the first row.

Now to the real test. I altered the order of the first table so that it looks like this:

Under the assumption that it keeps the first row, we expect to get the following table:

but instead we get this:

Here's the code for the tests in case anyone wants to check

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WclTSUUpUitWJVnKCs0BiSUqxsQA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [a = _t, b = _t]),
    Example = Table.TransformColumnTypes(Source,{{"a", type text}, {"b", type text}}),
    ExampleResult = Table.Distinct(Example, {"b"}),
    ReorderedExample = Table.Sort(Example,{{"a", Order.Descending}}),
    ReorderedExampleResult = Table.Distinct(ReorderedExample, {"b"})
in
    ReorderedExampleResult