Need help with Power Query

Leon_Redclifft 

If you mean something like this

you may add index column, after that custom column where to check if previous date is equal to current one then return null else date. Plus cosmetic.

let
    Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
    ChangeType = Table.TransformColumnTypes(
        Source,
        {{"A", type text}, {"Date", type date}}
    ),
    AddIndex = Table.AddIndexColumn(ChangeType, "Index", 0, 1),
    AddCustom = Table.AddColumn(
        AddIndex,
        "Custom",
        each
            if ([Index] > 0) and (AddIndex[Date]{[Index]-1} = AddIndex[Date]{[Index]})
            then null
            else [Date]),
    RemoveOtherColumns = Table.SelectColumns(AddCustom,{"A", "Custom"}),
    RenameColumns = Table.RenameColumns(RemoveOtherColumns,{{"Custom", "Date"}})
in
    RenameColumns