javascript - 七牛上传图片的问题

如果我一个页面、有两个地方上传图片但是我想他们的key不同，要怎么才能分开不冲突呢，我现在的做法是创建两个文件

var uploader1= Qiniu.uploader({
'Key': function(up, file) {
            var now = new Date();
            var date = now.getFullYear()+((now.getMonth()+1)<10?"0":"")+(now.getMonth()+1)+(now.getDate()<10?"0":"")+now.getDate();
            return "topic/cover/"+date;
        },
})
var uploader2= Qiniu.uploader({
    'Key': function(up, file) {
            var now = new Date();
            var date = now.getFullYear()+((now.getMonth()+1)<10?"0":"")+(now.getMonth()+1)+(now.getDate()<10?"0":"")+now.getDate();
            return "topic/banner/"+date;
        },
    })
})

但是这样做为什么key会相同呢