layui文件上传重复问题

upload.render({
            elem: '#add_ppts'
            ,url: localStorage.getItem('url') + '/upload/upload/ppt_upload'
            ,accept: 'video' //视频
            ,choose: function(obj){
                // var files = obj.pushFile();
                var files = this.files = obj.pushFile();
                console.log(files)
                obj.preview(function(index,file,result){
                    pt_name = file.name;
                    var size = parseInt(file.size)/1024;
                    size = size/1024;
                    pt_size = size;
                })
            }
            ,progress: function(e , percent) {
                    console.log("进度：" + percent + '%');
                    element.progress('progressBar',percent  + '%');
            }
            ,done: function(res,index){
                console.log(res)
                $("#fileName").val(res.data);
                var ppt_html = '';
                ppt_html +=
                '
'+
                '    '+ pt_name +''+
                '    '+ pt_size +'
'+
                '    重传删除