Been there done that and about to go again with the new 240D. Yup, you gotta take your title/registration along with the car so the parts guy can verify you're not getting keys for the ride up the street you've been eyeing.
But it's oh so nice to have a factory steel key to rule all the tumblers with! Did it on our 300DT and this new 240D has the same deal it did, one key for the ignition and another for everything else. Plus they're all brass keys. Pleh!