Continue on without re-type

[Aleadinglight]

Hello, I have a Vue instance like this:

var app = new Vue({
    el:'#app',
    data:{
        message: 'Hello',
        show:true
    },
    components: {
        VueTyper
    }
});

When I add more line to message, for example: app.message+=" \n Please help", the whole app.message is typed again twice. But I only want it to continue on typing the second message only. Is there any helpful feature on this or any idea how to work it out?