How to provide session persistence, when pushing data with push method?

Hi! I have a form and it send requests to the Laravel. Laravel controller catch requests and store data in session by push method, for example

$basename = pathinfo($path, PATHINFO_BASENAME);

if (!$request->session()->exists('upload')) {

    $request->session()->put('upload', []);
}

$request->session()->push('upload', $basename);

var_dump($request->session()->get('upload'));

When form sends two requests to Laravel, I expects to see in var_dump two values in array, but I see only one value. Why it can happening? Thanks in advance!