[Vuejs]-Data of child component is passed on to it next sibling component on update

This is always a good practice to add unique key to elements inside v-for loop.

Using unique keys allows to avoid weird behavior when you delete items from an array rendered with v-for. It helps Vue decide weither to render new data or show the cached one: https://v2.vuejs.org/v2/guide/list.html#key

Starting from Vue 2.2 using key is required when looping components: https://v2.vuejs.org/v2/guide/list.html#Components-and-v-for