[Vuejs]-Vuetify Datepicker- Enabled multiple property but showing wrong selected Dates count

I think from your code, your v-model data, $store.state[parentName].picker already have any value.

You can see this value using Vue.js devtools.
If don’t have any value on v-model, please anotate the comment.

If you already have any value, and you don’t expect
You should clear the $store.state[parentName].picker in beforeMount or beforeCreate.