Vue - Toggling similar elements with no keys

HTML

<div id="app">
  <div v-if="isUsername">
    <Label>Username</Label>
    <input v-model='data'/>
  </div>
  <div v-else>
    <Label>Email</Label>
    <input v-model='data' />
  </div>
  
  <button @click="toggle">
   Toggle
  </button>
  <span> {{data}} {{data2}}</span>
  
</div>

CSS

body {
  padding: 20px;
  font-family: Helvetica;
}

#app {
  background: #fff;
  border-radius: 4px;
  padding: 20px;
  transition: all 0.2s;
}

li {
  margin: 8px 0;
}

h2 {
  font-weight: bold;
  margin-bottom: 15px;
}

del {
  color: rgba(0, 0, 0, 0.3);
}

Vue

new Vue({
  el: "#app",
  data: {
    isUsername: true,
    data2: null,
    data: null
  },
  methods: {
  	toggle() {
    	this.isUsername = !this.isUsername
    }
  }
})