Timothy,

No one can tell if it is a good idea or not, because the best relational design in integrally combined with the actual business. If your two tables are Customers and Addresses the answer is one way, if it Cust1 and Cust2 then the answer is different.

Hypothetically discussing Master and Second tables gives no information about what the data is, and to determine the best design it is critical to know what the data is.