When you copy you duplicate, ie you will have one copy in suppliers-database and one copy in customers-database. While the Odoo solution has a single contacts-database.
That is what the thread OP suggested. I disagreed and suggested another approach with supporting information in that linked post.
Putting this discussion back on track to your actual question, @elainecpa, you can handle your situation using special accounts. Create a custom control account under Liabilities named Advances from Guests. Follow the procedures outlined in this Guide: Avoid automatic credit allocations with special accounts | Manager. This was previously explained in this topic in post #6 above.