使用Dropzone，jQuery和php上传表单 - 上传多个文件时没有个人响应

As stated, I have a problem with the response if I upload multiple files at once. For example, I upload a.jpg and b.jpg. In the next step, I upload b.jpg and c.jpg. My PHP script checks the names for duplicity and finds one in b.jpg but as response, I got each images flagged with

error - file already there.

I can't differ the responses individually.

I initialize my dropzone via jquery:

myDropZone = $("#dropzone").dropzone({
 autoProcessQueue: false,
 uploadMultiple: true,
 xx: xx

 init:function(){
     var self = this;
     // check error and some other states
     self.on("error", function (file, response) {
         console.log("error: "+file);
         console.log("error-response: "+response);
     }
     // set process
     $("#actions .start").click (function(file){
         self.processQueue();
     }
 }
});

I use uploadMultiple for multiple fileupload, I disabled the autoprocess and binded the function processQueue() to a button of my liking. So far so good.

No I have my php-script processing the data. It should be called once because of the uploadMultiple parameter.

if (!empty($_FILES)) {
    // resort array for easy processing
    for($i = 0 ;$i < count($_FILES['file']['name']) ; $i++) {
        $fileArrays[] = array_column ( $_FILES['file'], $i);
    }
    foreach($fileArrays as $file) {
        $upload = array();
        if(file_exists($file[0])) {
            $upload[] = "File already there.";
        }
        // some other validations...
    }
    if(empty($upload)) {
        //move_uploaded_file()
        http_response_code(200);
    } else {
        print_r($upload);
        http_response_code(404);
    }

But now all uploads get all responses, whether they are true or not. For example, I upload b.jpg and c.jpg, where b.jpg already exists. Both images get the success icon.

Now I upload d.jpg and c.jpg (note the order), where c.jpg already exists and both images the the error

File already there

Does anybody have the same problem with the response? Maybe I'm doing the php-validation wrong? Or do I have to handle the dropzone-event-parameter (success, etc.) in another way? I tried successmultiple, completemultiple, etc. but with no success.

"Solved" it by switching from ProcessQueue to:

self.getQueuedFiles().forEach(function(element) {
    self.processFile(element);
});

Brougth some other problems with it but they were solvable.