Option Explicit

    Sub Test()

        Dim wbR As Workbook, wbD As Workbook
        Dim wsR As Worksheet, wsD As Worksheet
        Dim LastrowR As Long, LastrowD As Long, i As Long, CountTimes As Long
        Dim PNR As String

        Set wbR = Workbooks("Recon.xlsm")
        Set wbD = Workbooks("DataExt.xlsx")

        Set wsR = wbR.Worksheets("Sheet1")
        Set wsD = wbD.Worksheets("Sheet1")

        'Let as assume that PNR column is column A, in Sheet 1, in both workbooks.
        'Also keep in mind that both workbooks should be open and have the following types (Recon -> .xlsm & DataExt ->  .xlsx)

        'Find the last row of PNR column in Recon File
        LastrowR = wsR.Cells(wsR.Rows.Count, "A").End(xlUp).Row
        'Find the last row of PNR column in DataExt File
        LastrowD = wsD.Cells(wsD.Rows.Count, "A").End(xlUp).Row
        'Loop PNR column in Recon File
        For i = 2 To LastrowR
            'Assign value to PNR
            PNR = wsR.Range("A" & i).Value
                'Count how many times PNR appears in column A DataExt file
                CountTimes = Application.WorksheetFunction.CountIf(wsD.Range("A2:A" & LastrowD), PNR)

                'If appears 1 time
                If CountTimes = 1 Then
                'If appears 2 times
                ElseIf CountTimes = 2 Then
                'If appears more than 2 times
                ElseIf CountTimes > 2 Then
                End If

        Next i

    End Sub