Diddums - the copied/cloned key I got was Silca brand and it was the immobiliser function and the blade together in a non-flip housing. So everything you need to unlock and start your car, but no remote/alarm function - remember this is totally separate. The locksmith told me they could not do the remote/alarm. This wasn't a great issue for me because this particular 156 did not have an alarm, so I only lost the remote lock/unlock, which actually doesn't work on the one original key I still have because the micro switches are stuffed.
My comment about 2002/2003 cars was related to Chris's note that typically only later (2004/2005) 156's had code 3 keys, and that code 2 keys cannot be cloned.