Show backed up secrets from file

[mihalt]

I use docker + file backend with command like this

sudo docker run --cap-add=IPC_LOCK -e 'VAULT_DEV_ROOT_TOKEN_ID={token}' -e 'VAULT_LOCAL_CONFIG={"storage": {"file": {"path": "/vault/file"}}, "listener": [{"tcp": { "address": "0.0.0.0:30001", "tls_disable": true}}], "default_lease_ttl": "168h", "max_lease_ttl": "720h", "ui": true}' -p "30001:30001" -v "/vault/file:/vault/file:rw" hashicorp/vault

I just copied /vault/file to another linux server to the same directory, installed vault with the same command and hoped, that I will able to see the same secrets by the same root token. But I've got error:
Error initializing Dev mode: Vault is already initialized

Can you say me, please, what did I do wrong? Can I see my backed up secrets or will you able to do feature that help to do it?