Given this entity class plus a matching Child class

public class Parent {
	@OneToMany(mappedBy = "parent")
	private List<Child> children;
}

This
em.createQuery("select distinct p from Parent p left join fetch p.children").getResultList();
yields a number of results equal to the number of Parents, as expected.

But this
em.createQuery("select distinct p from Parent p left join fetch p.children", Tuple.class).getResultList()
yields a number of results equal to the number of children if there are more than one child.

There is an executable demonstration of the issue: https://github.com/schauder/duplicate-parent-entities/blob/master/src/test/java/io/github/cepr0/demo/repo/EmTest.java