cept it isn't just the belt, its the tensioners, bolts and water pump, your probably right and its the same gear and possibly even QC'd the same, but probably isn't good enough for the sake of 20 quid.
No "probably" about it. Tensioners also had Gates markings. Water pump is another matter. Although on engines like Zetec silvertops, where the cambelt had to come off to change the pump, on later engines that's not always the case and a cambelt kit doesn't usually include the waterpump. You usually have to buy that separately.