Private Sub Command44_Click()
    On Error GoTo Handler

    ' Require an existing record
    If Me.NewRecord Then
        MsgBox "Please select an existing record to duplicate.", vbExclamation
        Exit Sub
    End If

    ' Ensure form allows new records
    If Me.AllowAdditions = False Then
        MsgBox "This form does not allow adding records.", vbExclamation
        Exit Sub
    End If

    ' Duplicate current record
    DoCmd.RunCommand acCmdSelectRecord
    DoCmd.RunCommand acCmdCopy
    DoCmd.RunCommand acCmdPasteAppend

ExitHere:
    Exit Sub

Handler:
    MsgBox "Duplicate failed: " & Err.Number & " - " & Err.Description, vbCritical
    Resume ExitHere