Use VBA to copy sheet number of times based on cell?

Something like this perhaps.

Sub Duplicate()
Dim wsMain As Worksheet
Dim wsNew As Worksheet
Dim CartonNo As Long

    Set wsMain = Sheets("Sheet1")
    
    For CartonNo = 1 To wsMain.Range("A6").Value
        wsMain.Copy After:=Sheets(Sheets.Count)
        Sheets(Sheets.Count).Range("A8").Value = CartonNo
    Next CartonNo
    
End Sub