I have been experiencing this problem. What we are all trying to do here is make sure that a second request isn't made to the same controller and action as is sent when the page loads. What is causing this problem is requests being made for files that are not there. What I found the solution was is logging the controller name and action name everytime a request is made to find out which files are being requested and not found..
For many, this will be the favicon.ico or the robots.txt file.
For me the problem was a little different:
I was hosting a version of jquery on my server at js/jquery.min.js. What I found is that everytime I loaded a page that used this jquery file a request was made looking for js/jquery.min.map and since I didn't have that file in the js directory it went looking for it inside phalcon by looking for the js controller with the jquery.min.map action. When it couldn't find that another request was sent to the same controller and action as before. In my case this could have been index/index or login/index, it could have been any combination. The solution was for me to put in the jquery.min.map file from code.jquery.com/jquery.min.map. Then the same thing happened again where requests were made for jquery.js ( This is the web inspectors looking for these ). So I put in the jquery.js from code.jquery.com/jquery.js. After doing that there were never any unwanted requests made again.
The point here is that you need to make sure that all files that are being requested are found, or you need to change you code so that those files are not requested at all ( you could have just loaded jquery from the jquery domain instead of your own web server ). In order to check out which files are being requested and not found, make sure to log dispatcher information like so:
$controller = $dispatcher->getControllerName ();
$action = $dispatcher->getActionName ();
Phalcon\DI::getDefault()->get('logger')->debug( $controller .' '. $action );
What my log showed when I was experiencing the issue:
[Tue, 24 Nov 15 19:32:00 +0000][DEBUG][][] index index
[Tue, 24 Nov 15 19:32:00 +0000][DEBUG][][] js jquery.min.map
[Tue, 24 Nov 15 19:32:00 +0000][DEBUG][][] index index