I understand what you鈥檝e done so far and the reasoning behind it. If your goal is to have a consolidated list of unique people, you should run auto-dedupe on the person鈥檚 LinkedIn URL (rather than the post鈥檚 URL). This will ensure each individual only appears once in the table.
However, you mentioned that it鈥檚 difficult to accurately track how frequently a particular individual has interacted across different posts. If your goal is to see how many times-and on which posts-a person has interacted, you鈥檒l actually need to keep those multiple entries, with each row linking the person to a specific post.
Could you clarify your main objective? Are you looking for a unique list of people, or do you want to track all interactions each person has had across different posts?