为什么批量上传照片，后台接收到的照片会有重复的？前台选照片的时候是没有选择重复的

我的JS代码如下：
//上传图片 批量上传 start
var files = [];
var index = 1;
var newUrlAfterCompress;
// checkPicNum可上传照片张数，picType照片类型，appSessionIdInfo移动端的请求唯一标识
function choosePhoto(event,checkPicNum,picType,appSessionIdInfo,taskId,menuId){
if (mui.os.plus) {
var buttonTit = [{
title: "我要拍照美美哒"
}, {
title: "从手机相册选择"
}];

    plus.nativeUI.actionSheet({  
        /* title: "上传图片", */  
        cancel: "取消",  
        buttons: buttonTit  
    }, function(b) { /*actionSheet 按钮点击事件*/  
        switch (b.index) {  
            case 0:  
                break;  
            case 1:  
                getImage(picType,appSessionIdInfo,taskId,menuId); /*拍照*/  
                break;  
            case 2:  
                galleryImg(checkPicNum,picType,appSessionIdInfo,taskId,menuId); /*打开相册*/  
                break;  
            default:  
                break;  
        }  
    })  
}  

}
// 拍照获取图片
function getImage(picType,appSessionIdInfo,taskId,menuId) {
var c = plus.camera.getCamera();
c.captureImage(function(e) {
plus.io.resolveLocalFileSystemURL(e, function(entry) {
var imgSrc = entry.toLocalURL() + "?version=" + new Date().getTime(); //拿到图片路径
var imgId = getUid();
if(picType!=9){//非上传头像
setHtml(imgSrc,imgId);
}
var dstname = "_downloads/" + imgId + ".jpg"; //设置压缩后图片的路径
newUrlAfterCompress = compressImage(imgSrc, dstname,picType,appSessionIdInfo,taskId,menuId,imgId);
appendFile(dstname, imgSrc);
}, function(e) {
console.log("读取拍照文件错误：" + e.message);
});
}, function(s) {
console.log("error" + s);
}, {
filename: "_doc/camera/"
})
}
// 从相册中选择图片
function galleryImg(checkPicNum,picType,appSessionIdInfo,taskId,menuId) {
plus.gallery.pick(function(e) {
for (var i in e.files) {
var fileSrc = e.files[i];
var imgId = getUid();
if(picType!=9){//非上传头像
setHtml(fileSrc,imgId);
}
var dstname = "_downloads/" + imgId + ".jpg"; //设置压缩后图片的路径
newUrlAfterCompress = compressImage(e.files[i], dstname,picType,appSessionIdInfo,taskId,menuId,imgId);
appendFile(dstname, fileSrc);
}
}, function(e) {
console.log("取消选择图片");
}, {
filter: "image",
multiple: true,
maximum: checkPicNum,
system: false,
onmaxed: function() {
console.log('最多只能选择'+checkPicNum+'张图片');
plus.nativeUI.alert('最多只能选择'+checkPicNum+'张图片');
}
});
}

function setHtml(e,imgId) {
/ var divHtml = "<div class=\"a-add\"><img src=" + encodeURI(e) +
" class=\"file_img\" style=\"width:96px;height:96px\"><img src=\"../../images/remove.png\" class=\"a-remove\"></div>";
$("#imgDiv").prepend(divHtml); /
var html = '<li class="mui-table-view-cell liCss" style="height: 178px;">';
html = html + '<table style="width: 115%;height: 100%;">';
html = html + '<tr style="height: 100px;">';
html = html + '<td style="width: 45%;" rowspan="2">';
html = html + '<img data-preview-src="" data-preview-group="1" src="'+encodeURI(e)+'" id="imgInfo" class="imgCss"/>';
html = html + '</td>';
html = html + '<td style="width: 55%;text-align: right;">';
html = html + '<textarea placeholder="请输入照片描述,100个字符以内..." class="textareaCss"></textarea>';
html = html + '</td>';
html = html + '</tr>';
html = html + '<tr style="height: 50px;">';
html = html + '<td>';
html = html + '<button type="button" id="lookPic" class="mui-btn mui-btn-primary detailBtnCss" style="margin-left: 5%;">';
html = html + '保存照片描述';
html = html + '</button>';
html = html + '</td>';
html = html + '</tr>';
html = html + '</table>';
html = html + '<div class="loadingDiv" id="'+imgId+'">';
html = html + '<div style="width: 100px;height: 50px;margin: 0 auto;margin-top: 12%;">';
html = html + '<div class="mui-spinner" id="'+imgId+'loading" style="margin-top: 15%;font-size: 1rem;float: left;line-height: 50px;"></div>';
html = html + '<div style="float: right;line-height: 50px;color: yellow;" id="'+imgId+'loadingInfo">上传中...</div>';
html = html + '</div>';
html = html + '</div>';
html = html + '</li>';
$("#imgList").append(html);
}
//压缩图片，无return
function compressImage(src, dstname,picType,appSessionIdInfo,taskId,menuId,imgId) {
plus.zip.compressImage({
src: src,
dst: dstname,
overwrite: true,
quality: 20
},
function(event) {
console.log("压缩一张照片成功:"+event.target);
upload(picType,appSessionIdInfo,taskId,menuId,imgId);
//return event.target;
},
function(error) {
console.log("压缩一张照片出错:"+event.target);
//return src;
});
}
// 产生一个随机数
function getUid() {
//return Math.floor(Math.random() * 100000000 + 10000000).toString();
return generateUUID();
}

function appendFile(p, fileSrc) {
console.log("name=="+"img" + index);
console.log("path=="+p);
files.push({
name: "img" + index, //这个值服务器会用到，作为file的key
path: p,
fileSrc: fileSrc
});
index++;
}
//上传文件
function upload(picType,appSessionIdInfo,taskId,menuId,imgId) {
//mui.showLoading("上传中,请稍后...","div");
var url = "";
if(picType == 9){
url = path1 + "/uploadPic/uploadImageForHead?appSessionIdInfo="+appSessionIdInfo;
}else{
url = path1 + "/uploadPic/uploadImageForMyApp?appSessionIdInfo="+appSessionIdInfo;
}
console.log("上传照片=="+url);
var task = plus.uploader.createUpload(url, {
method: "POST"
},
function(t, status) {
//mui.hideLoading();
if (status == 200) {
console.log("上传成功，状态码=="+status+",t=="+JSON.stringify(t));
var rCode = JSON.parse(eval(t).responseText).code;
var rPicName = JSON.parse(eval(t).responseText).picName;
var rMsg = JSON.parse(eval(t).responseText).msg;
if(picType == '9'){//上传头像一张
if(rCode=='0'){
mui.alert(rMsg);
$("#imgInfo").attr("src",path1+"/uploadPic/showPic?pictureName="+rPicName+"&appSessionIdInfo="+appSessionIdInfo);
}else{
mui.alert(rMsg);
}
}else{//上传多张检修照片
if(rCode=='0'){
$("#"+imgId).css("display","none");
mui.toast(rMsg);
}else{
$("#"+imgId+"loadingInfo").text(rMsg);
$("#"+imgId+"loading").removeClass("mui-spinner");
mui.toast(rMsg);
}
}

        } else {  
            console.log("请求失败，状态码=="+status);  
        }  
    }  
);  
//添加其他参数  
for (var i = 0; i < files.length; i++) {  
    var f = files[i];  
    task.addFile(f.path, {  
        key: "imgFile"+i  
    });  
}  

if(picType != 9){// 9代表是头像照片  反之代表的是各个检修类型的照片  
    //大坑之处，传的参数值不能是数字0，数字0的话后台取不到 必须大于1的数字  
    // 要传0的话 必须转字符串0  
    task.addData("pictureType", picType.toString());  
    task.addData("taskId", taskId);  
    //menuId 针对年检  
    //task.addData("menuId", menuId);  
}  
task.start();  

}