nginx and fcgiwrap - one response per IP?

I found this comment:

There is one "feature" to watch out for in a nginx + fastcgi setup. A given PHP script will only run once for a given IP. So, if the same IP loads index.php for a website twice at the same time, index.php will be served sequentially: The second index.php load will not be processed until the first index.php load is complete.

On this page: https://www.samiam.org/blog/20110702.html

Is this true? I couldn't find any other reference to this "feature".

I am wondering if I am hitting this feature, and if it can be configured?

I have a CGI program and want to run it using fcgiwrap and nginx. It is a long running but lightweight process, with a limited number of maximum hits possible due to limited number of clients.

The same client may issue multiple requests in parallel. This should be allowed, and processed in parallel.

It is behind an nginx proxy (no buffering), which forwards on to a second nginx server.

I've set FCGI_CHILDREN=200 in /etc/default/fcgiwrap and yet I only ever see one process executed at once.