=СЧЁТ(1/(ПОИСКПОЗ(ОКРУГЛВНИЗ(A$3:A$7;);ЕСЛИ(B$3:B$7=D3;ОКРУГЛВНИЗ(A$3:A$7;));)=СТРОКА(A$3:A$7)-2))

=СЧЁТ(1/ЧАСТОТА(($B$3:$B$7=D3)*ОТБР($A$3:$A$7);ОТБР($A$3:$A$7)))

Option Explicit
Function tt(login As String, BD As Range) As Long
    Dim arr(), i As Long, dict As Object, d As String
    If BD.Columns.Count <> 2 Then
        tt = -1
        Exit Function
    End If
    If BD.Rows.Count < 2 Then
        If BD.Cells(1, 2) = login Then tt = 1 Else tt = 0
        Exit Function
    End If
    arr = BD
    Set dict = CreateObject("Scripting.Dictionary")
    With dict
        For i = 1 To UBound(arr)
            If arr(i, 2) = login Then
                d = Format(arr(i, 1), "ddmmyyyy")
                If Not .exists(d) Then
                    .Add Key:=d, Item:=0
                End If
            End If
            tt = .Count
        Next
    End With
End Function