After years of using knock-off devices, it might be time for proper fitted custom cage. I know MM is serious about not sending out replacement keys for their security screws, but can 2 keys for 1 screw be purchased when ordering a new cage? I always have an emergency key on me, whether it's a padlock device or a hidden barrel lock. We always come up with a tamper proof method so my wife will know if I had to use it. I never have but we both insist that I have it available.
I believe you will receive 2 keys with your device Coincidentally, my Wife may have misplaced one of Her two keys. I think MM will require Her to call to request a replacement key.
Another thing that might be true is if you order a 2nd device from them and you already have keys... I do not think you get extra ones... I could be wrong about this though.