Rest API for updating customer `PUT` method not working. Every time creating new customer.

> Method: PUT
> 
> Request URL: http://localhost/magento/rest/en/V1/customers/55

**Body:**

    {
       "customer": {
         "email": "[email protected]",
         "firstname": "firstname new",
         "lastname":  "lastname new",
         "website_id": 1
       }
    }

Also when pass the customer Email Id then response is throwing below error.

**Response:**

    {
        "message": "A customer with the same email address already exists in an associated website."
    }