In [this introductory tutorial](https://docs.oracle.com/javase/tutorial/jdbc/overview/index.html) on JDBC and Relational Databases, it is stated,

> 
> **Integrity Rules**
> 
> 
> Relational tables follow certain integrity rules to ensure that the
>  data they contain stay accurate and are always accessible. First, the
>  rows in a relational table should all be distinct. **If there are
>  duplicate rows, there can be problems resolving which of two possible
>  selections is the correct one.**
> 
> 
> 

But if the rows are duplicate, it means all the fields in both the rows hold the same values; and when they are completely same (duplicate), how does the question of one being correct and the other being incorrect arise? **How does the duplication of a row harm the data integrity?**