The post asks whether a proxy URL will rotate with each URL. The comments indicate that the proxy IP is the same based on the user's proxy settings, and the proxy makes requests to the page under random IPs available in the proxy group. One community member suggests that the rotation is done automatically by the crawler. However, there is no explicitly marked answer to the original question.
Proxy IP is the same per your own proxy settings, so you calling same proxy URL and then proxy doing requests to page under random IPs available in proxy group.