Event click multiplying

Question

I have a directory listing system that displays files and folders, when I click on an item, it displays a (single) menu that is already set on the page and can be used by all files. In this menu, there is an option called DELETE, the problem is there. To open the menu have to click, however, I need to know what was the id of the file chosen to use in the deleteFile function:

var files = document.getElementsByClassName("backgroundFiles");
for(i=0;i<files.length;i++){
    files[i].addEventListener("click", function(event){
        menuFiles(this.id, event.clientX, event.clientY);
        deleteFile(this.id);
    });
}

In deleteFile there is another click event that will be triggered when the user clicks on the DELETE menu option:

function deleteFile(idElement){
    document.getElementById("a_dele").addEventListener("click", function(event){
        var chave = prompt("Digite a chave de segurança");
        ...
    });
}

The problem is that these events are multiplying, when giving the first click everything is ok, already in the second, appears twice the prompt, in the third click appears three times the prompt and so on. Someone could help me with a solution?