Restore: DB metadata not changed. database may already exist version 1.8.1

When I try to restore a database it is failing. I am getting the following:
error restore: DB metadata not changed. database may already exist.

Does anyone know how I can resolve this?

Maybe you could tell us:

a) how are you restoring the database

b) is the message correct, and the database already exists ?

Antony.

I am using what the documentation says. It is something like the following:
influxd restore -portable -db mymondb -newdb mymondb_bak path-to-backup