Function hf_cache_root 

pub fn hf_cache_root(
    environment: &HashMap<String, String>,
    home: &Path,
) -> PathBuf

The machine’s Hugging Face hub cache: $HF_HUB_CACHE, else $HF_HOME/hub, else ~/.cache/huggingface/hub.

There is exactly one, because that is the rule the hub’s own tooling follows: the environment says where the cache is, replacing the default rather than adding to it. A cache elsewhere that should also be swept is a setting (hf_cache_roots), not an environment variable, so what a pull writes and what discovery reads can never come apart.