How can I display in a select widget values that have some similarities?

Hi everyone.
I have in my PostgresDB a table where I save the employees (user_id, name, surname, dob) of an enterprise and I would like to display a select where is possible to pick an employee. The problem is that I have in the table employees with the same surname and some with the same name and the select widget returns this error:
"Duplicate values found for the following properties, in the array entries, that must be unique – value.
How can I solve this problem? Thanks.

@Gianluca As the user_id would be unique, you can use that as the value in the label-value pair, and the name + surname as label. Sharing an example below.

{{ => {return { "label": + ' ' + item.surname, "value": item["user_id"]}})}}