There are situations where several filesystems reside on a single encrypted LUKS device (e.g. when using BTRFS subvolumes). Simply generating a `boot.init.luks.devices.NAME.device` entry for each mounted filesystem will result in an error later when evaluating the nix expression in `hardware-configuration.nix`.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.