In short, this option is available. Each event batch can contain more than one event, as long as they are for the same user. Although in testing we see that multiple batches are ingested much like is being reported when sent in an array, there may be other ramifications unaccounted when using the endpoint in this way.
As an option that's well documented and purpose-built to handle multiple batches in the same call, the/v2/bulkevents endpoint can be used. Currently, it's possible to use this endpoint to send more than one event batch. For safety and stability reasons we would recommend using this one. Our documentation states that if more than one event batch needs to be sent, then the /v2/bulkevents is the correct endpoint.