Spring Data JPA: One to Many Mapping : SQLIntegrityConstraintViolationException

I have two Entity classes Customer and Product, Where One customer can buy Multiple Products (One to Many Mapping)

@Entity
public class Customer {
    @Id
    @GeneratedValue
    private int id;
    private String name;
    private String email;
    private String gender;
    @OneToMany(targetEntity = Product.class,cascade = CascadeType.ALL)
    @JoinColumn(name ="cp_fk",referencedColumnName = "id")
    private List<Product> products;
}

@Entity
public class Product {
    @Id
    private int pid;
    private String productName;
    private int qty;
    private int price;
}

Its working fine when One customer having multiple Products.

Issue comes when existing product bought by a customer is also bought by another customer.

Request Payload 1: (It works fine creates a user basant and two products)

{
    "customer": {
        "name": "Basant",
        "email": "b@gmail.com",
        "gender": "male",
        "products": [
            {
                "pid": 201,
                "productName": "Mobile",
                "price": 10000,
                "qty": 1
            },
            {
                "pid": 399,
                "productName": "Laptop",
                "price": 200000,
                "qty": 3
            }
        ]
    }
}

Request Payload 2 : (This request will give java.sql.SQLIntegrityConstraintViolationException: Duplicate entry '201' for key 'product.PRIMARY')

{
    "customer": {
        "name": "Santosh",
        "email": "s@gmail.com",
        "gender": "male",
        "products": [
            {
                "pid": 201,
                "productName": "Mobile",
                "price": 10000,
                "qty": 1
            },
            {
                "pid": 286,
                "productName": "clothes",
                "price": 40000,
                "qty": 2
            }
        ]
    }
}

How can we make sure Santosh is also able to buy same Mobile which Basant bought? Could you please help me with this