When I upload an image to firebase storage and retriving the download url and displaying in img tag but it is showing multiple times

I am uploading an image to firebase storage and again storing the URL path in the firebase database. However when I upload the first time it is displaying a single time, but when I upload again to the gallery and select an image it is displaying two times. If again I go to the gallery and select an image it is displaying three times. Please guide me how to solve this.

<img id="image5e" src="img/upload.png" />
<input type='file' style="display:none;" name="photosubmit" id="photosubmit"/>

var app = {
    initialize: function() {
        app.bindEvents();    
    },
    bindEvents: function() {
        document.addEventListener('deviceready', this.onDeviceReady, false);
    },
    onDeviceReady: function() {
         var uploadimg = document.getElementById("image5e");
         uploadimg.addEventListener("click",app.upload2gallery,false); 
    },         
    upload2gallery: function() {
     $("#photosubmit").click();

     var filebutton = document.getElementById("photosubmit");
     filebutton.addEventListener('change', function(e) {
         var file = e.target.files[0];    
         var storageRef = firebase.storage().ref('sweet_gift/' + file.name);    
         var task = storageRef.put(file);

         task.on('state_changed', function progress(snapshot) {
            var load = '<h1>Please Wait</h1>' + '<i class="fa fa-circle-o-notch fa-spin fa-3x fa-fw"></i><span>Loading ...</span>';
            $.mobile.loading('show', {
                text: 'Please wait...',
                textVisible: true,
                html: load,
                theme: 'z'
            });
        }, function error(err) {
        }, function complete() {
            $.mobile.loading('hide');

            var uni = localStorage.getItem("lunicode");
            var ref = firebase.database().ref(uni);
            var myname = storage.getItem("uname");
            var myid = storage.getItem("myid");
            var downloadURL = task.snapshot.downloadURL;
            ref.push({
                name: myname,
                imageurl: downloadURL,
                photoUrl: "/images/profile_placeholder.png",
                my_id: myid,
            });
        });
    });
},

$(document).on('pagebeforeshow', '#chatpage', function() {
    var uni = localStorage.getItem("lunicode");
    var ref = firebase.database().ref(uni);

    $("#images6").empty();

    ref.orderByChild("messages").on("child_added", function(snapshot) {
        $("#images6").append(movielist(snapshot.val()));
        var last_li = $(".cmsg li:last-child").offset().top;
        setTimeout(function() {
            $.mobile.silentScroll(last_li);
        }, 50);
        ActivityIndicator.hide();
    });
});

$(document).on('pagebeforehide', '#chatpage', function() {
    alert("going");
    var uni = localStorage.getItem("lunicode");
    var ref = firebase.database().ref(uni);
    $("#images6").empty();
    //ActivityIndicator.show();
    ref.orderByChild("messages").off("child_added");
    //ActivityIndicator.hide();
    $('#cmessage').val('');
});