duplicated requests with different status code & timing

[ctf0]

not sure if this is the normal behavior but this only happens on live server, in localhost all works without any issues.

// main template
<section class="pjax-container">
     // pages gets loaded here dynamically
</section>

$(document)
    .on('ready pjax:success', function() {
        // ...
    })
    .pjax('.links', '.pjax-container')
    .on('pjax:start', function() {})
    .on('pjax:complete', function() {});

$.pjax.defaults.timeout = 4000;