Nixpkgs does carry more than one version of some packages, but only when the maintainers deem it necessary. These are treated as separate packages with differen

Nixpkgs does carry more than one version of some packages, but only when the maintainers deem it necessary. These are treated as separate packages with different names. In the case of OpenSSL, Nixpkgs currently has two packages named openssl_1_0_2 and openssl_1_1, with openssl being an alias for latter. Different programs depending on different versions can be installed at the same time without conflict. Full paths to dynamic library files are used in binaries instead of relying on a global library path.