Sub CertificatePrint()
Dim iStart As Integer, iEnd As Integer, i As Integer, StrArry
On Error GoTo ErrHandler
iStart = CInt(InputBox("What is the first Certificate to print?", "Print Certificates From", "1"))
iEnd = CInt(InputBox("What is the last Certificate to print?", "Print Certificates To", iStart + 1))
If iStart = 0 Or iStart > iEnd Then Exit Sub
With ActiveDocument
  For i = iStart To iEnd Step 2
    With .Shapes(1).TextFrame.TextRange.Fields(1)
      StrArry = Split(.Code.Text, " ")
      .Code.Text = Replace(.Code.Text, StrArry(UBound(StrArry)), i)
      .Update
    End With
    With .Shapes(2).TextFrame.TextRange.Fields(1)
      StrArry = Split(.Code.Text, " ")
      .Code.Text = Replace(.Code.Text, StrArry(UBound(StrArry)), i + 1)
      .Update
    End With
    .PrintOut
  Next
End With
ErrHandler:
End Sub