This seems to be a question that blurs the line between physical and IT security, but I'm hoping it's relevant enough!
In order to meet with PCI standards, our company recently switched from an open door with after-hours hand scanner, to an RFID+Security badge system.
I was just informed today (it wasn't part of our training procedures, hooray!) that keeping the RFID key fob on the same lanyard/chain/etc as ones ID badge is verboten. Now to me this seems absolutely pointless and probably more dangerous, because now if either my fob or badge is stolen it seems that the reasonable assumption would be "Oh, I just misplaced it/forgot it/it fell off in my car/etc."
Is there any valid reason to prohibit physically connecting (e.g. sticking them on the same keyring) the identification mechanism (my badge) from the authentication mechanism (my fob)?