Final answer:
In a natural join, the column on which the join is made appears only once in the resulting table, not twice. It automatically combines the tables based on columns with the same names and data types, eliminating duplicate columns.
Step-by-step explanation:
A natural join is a type of SQL join that is used to combine tables where columns have the same name and datatype. When a natural join is performed, it matches rows from the two tables being joined on these common columns. The crucial point to understand is that the column on which the join is made does not occur twice in the resulting table. Instead, the joined table will contain only one column for each of the matching column names.
In other words, in a natural join, there is an implicit assumption that the columns used for joining have not only the same name in both tables but also hold equivalent data. The database system automatically uses these columns to perform the join. Hence, for every unique pair of equivalent columns, only one column is present in the result set, thereby eliminating duplicate columns.