How to prevent employees from creating duplicate contact in Benefits

We are looking for possibilities on how to prevent employees entering duplicate contact in Me>Benefits>Before you Enroll>People to Cover

I have gone through few community posts on the same requirement; however, we do not have a solution yet on those threads.

We do not have auto complete rule set up in responsive for us to use the same in redwood.

Please let us know if there is any validation rule working using VB to restrict duplicate entries on benefits redwood pages