Remove Duplicate by comparing dates

See the working here - Open a blank query - Home - Advanced Editor - Remove everything from there and paste the below code to test (later on when you use the query on your dataset, you will have to change the source appropriately)

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMtY31DcyMDJS0lFyBGL31KLcxLxKpVgdFCknIHbNS89JzEuBShnjljKBSTljGGgKk3IB4uCCxMw8sIQRbkfglTLC5Qgj3I4wwuUIQxw2xQIA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Date = _t, Group = _t, Country = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Date", type date}, {"Group", type text}, {"Country", type text}}),
    #"Added Custom" = Table.AddColumn(#"Changed Type", "CurrentPreviousMonth", each [Date]>=Date.AddMonths(Date.StartOfMonth(Date.From(DateTime.FixedLocalNow())),-2) and [Date]<=Date.AddMonths(Date.EndOfMonth(Date.From(DateTime.FixedLocalNow())),-1)),
    #"Filtered Rows" = Table.SelectRows(#"Added Custom", each ([CurrentPreviousMonth] = true)),
    #"Removed Columns" = Table.RemoveColumns(#"Filtered Rows",{"CurrentPreviousMonth"}),
    #"Added Custom1" = Table.AddColumn(#"Removed Columns", "Month", each Date.Month([Date])),
    #"Grouped Rows" = Table.Group(#"Added Custom1", {"Month"}, {{"Temp", each _, type table [Date=nullable date, Group=nullable text, Country=nullable text, Month=number]}}),
    #"Added Custom2" = Table.AddColumn(#"Grouped Rows", "Custom", each Table.Distinct([Temp], {"Group", "Country"})),
    #"Expanded Custom" = Table.ExpandTableColumn(#"Added Custom2", "Custom", {"Date", "Group", "Country"}, {"Date", "Group", "Country"}),
    #"Removed Columns1" = Table.RemoveColumns(#"Expanded Custom",{"Month", "Temp"})
in
    #"Removed Columns1"