Prevent Duplicate entries in multiple column from VBA Userform

Dear Team,

I have a vba userform which enters data into multiple sheets. For two comboboxes, there can be "X" combinations like as follows:

Column B Column C
John Red
John Black
Michael Red
Michael Black

I want to prevent duplicate entries into columns. Currently I am using following code but it doesn't allow me to add multiple combinations. e.g. It won't allow me to add "Michael Red" if I have added "John Red" earlier in sheet.

With ws
        If Not (WorksheetFunction.CountIf(ws.Range("D:D"), ComboBox6.Value) > 0 And WorksheetFunction.CountIf(ws.Range("E:E"), ComboBox3.Value) > 0) Then

               
        .Cells(emptyRow, 1).Value = ComboBox7.Value
        .Cells(emptyRow, 2).Value = ComboBox8.Value
        .Cells(emptyRow, 3).Value = ComboBox9.Value
        .Cells(emptyRow, 4).Value = ComboBox6.Value
        .Cells(emptyRow, 5).Value = ComboBox3.Value
        .Cells(emptyRow, 6).Value = TextBox1.Value
        Response3 = MsgBox("Do you want to add more data", vbYesNo)
                If Response3 = vbYes Then
                    ComboBox3.Value = Null
                    ComboBox6.Value = Null
                    TextBox1.Value = Null
                Else
                    End If
    
        
        Else
            MsgBox ("Warning:Duplicate Entries Found. Please edit existing entries")
        End If

      End With
End If

Please help for this query.