No - you can not create another contacts db. Contacts recordset is designed to store contact's information. If you need to extend this recordset because you need some extra information then just add extra fields.
As a real estate agent you will probably need some special modules to keep track of your real estate inventory, but to some extent you can accomplish some automation using combination of contact/companies and Sales Opportunity module (available for free in Epesi Store) and extending both with some extra fields.
