Blesta can send those notices so that you can disable them in Enom. Many registrar modules only include the cost, not a price you set in their panel. If we used the price you set in Enom for Enom, then 1) Everyone would have to set a price there and 2) it would not work the same as other registrars who do not have a retail price, but only a wholesale price.
It is better to let Blesta do the price markup, or just set your TLD prices manually to the same value you have set for retail prices in Enom. If you want to make a modification to your module, and keep your markup at 0% for new/renew/transfer, you are welcome to do that, it's just not a change we would make to the module as it would be inconsistent with other integrations.