Since we have millions of domains in our database the risk is that sometimes 1 or 2 is taken already, we scan the database every day for availability. But due to the size of the database and number of domains, there is a risk that some might be taken already. We do an EPP check against the registrar when you try to order a domain that is listed as available if it is we will add it to your cart and you can register it right away.
Please note that we never guarantee any domain until the payment is processed and the domain is registered under your name.