Using v-select reduce with nested values but prohibit creation of duplicates in options

[u-till]

Hi there, i am trying to implement this example here from the docs, but i am trying to avoid the creation of duplicates by title as unique identifier:

https://vue-select.org/guide/values.html#tagging

const options = [
    {
        title: "HTML5",
        author: {
            firstName: "Remy",
            lastName: "Sharp"
        }
    }
];


<v-select
    taggable
    multiple
    label="title"
    :options="options"
    :create-option="book => ({ title: book, author: { firstName: '', lastName: '' } })"
    :reduce="book => `${book.author.firstName} ${book.author.lastName}`"
/>

If i create a new tag called "HTML5" it will create one, because the rest of the object is not matching.
I need to somehow filter the existing tags only by its title property and ignore the rest of the object.
I've tried for hours now but did not get it to work.
Can anyone help me out?