Wp post meta add (WP-CLI)

$ wp help post meta add

NAME

  wp post meta add

DESCRIPTION

  Add a meta field.

SYNOPSIS

  wp post meta add <id> <key> [<value>] [--format=<format>]

OPTIONS

  <id>
    The ID of the object.

  <key>
    The name of the meta field to create.

  [<value>]
    The value of the meta field. If omitted, the value is read from STDIN.

  [--format=<format>]
    The serialization format for the value.
    ---
    default: plaintext
    options:
      - plaintext
      - json
    ---

What happens if you apply this command to an existing meta field? I suspect it created an additional meta field with the same name (but other ID).