If you follow through to the story that shows a picture of the keys two things are notable: these are pretty easy keys to duplicate (especially given the nice clear photograph of them) and it was the New York Post who both broke the original story and posted a picture of the keys (face palm).
I was slightly surprised that they just look like regular keys. I was half expecting them to have special grooves, or protrusions, or magnets or something.
Nope. Just a regular key that hits a specific set of pins that are required to be there.
If you think about it, designing a lock that takes 2 completely different types of keys would be very difficult. If you don't fit the grooves that a regular key does, you don't fit. So you have to use the same blank. After that it is just the set of grooves that matters.
>designing a lock that takes 2 completely different types of keys would be very difficult
This is actually fairly common in commercial buildings. The keys have a channel running down the side (the 'grooves' you speak of). The grooves determine what kind of keyway the key can fit into. You can can configure your locks so a certain groove pattern will only fit a subset of your locks, while another kind of groove will fit into all of them. Schlage for instance makes a series of keyways (A, C, D, E, F, G, H, J, K, L, M, XP etc.) that are specified to do exactly this. I always forget which, but I believe it's the L keys that will fit into most of the other keyways.
Ancient is the point - at some point after the twenties, it became less and less cost effective to have someone at the building 24/7 - and the rise of electronic security (alarms basically) provided everyone with a two-factor reassurance that the system was still secure even with distributed master keys.
