Duplicating a car key requires a key duplicator. You must have a working key present so the auto locksmith can duplicate a key. Duplicating a car key is different from cutting the key by code, which can be programmed to cut a key based on the numerical representation of its physical appearance. A key duplicate may have some amount of automation, but it requires an existing key to be examined in order to cut a copy of that key.
An experienced Auto Locksmith is required to run a key duplicator. The machine needs to be oriented properly between its blade and the key reader. Between these different calibrations, a lot could go wrong for a novice so the key must be set up correctly in the key duplicator. This process uses a bit of artistry, it is not an exact science. This will not stop your key from working correctly unless you are using a copy of a copy to make your duplicate. The farther removed a particular copy is from the original, the greater the chances of it not working in the car. Always give the auto locksmith the original key (or the closest to it that you have) when you are requesting car key duplication.