[Vue warn]: Duplicate keys detected: x. This may cause an update error

Same key for different v-for loops causing this warning. You can avoid this using different key for different v-for loops.

    <div v-for="(item, i) in items" :key="i"></div>

    <div v-for="(item, i) in items2" :key="'A'+ i"></div>

    <div v-for="(item, i) in items3" :key="'B' + i"></div>

Here, A and B are just sample characters. You can basically use any character instead of those (just for uniqueness).