hql group by on multiple classes generates 1 query by class and can return a wrong number of results

The classes DomesticDog and DomesticCat extend / implement Pet.

Here is the data of the 2 tables :

DomesticDog
+----+----------------------+
| 1 | Max |
| 2 | Buddy |
| 3 | Jake |
| 4 | Buddy |
+----+----------------------+

DomesticCat
+----+----------------------+
| 1 | Tiger |
| 2 | Smokey |
| 3 | Tiger |
| 4 | Max |
+----+----------------------+

Given the HQL query :

select pet.name from Pet pet group by pet.name having count(pet) > 1

Two SQL queries are generated and executed separately :

select domesticdog0_.name as col_0_0_ from DomesticDog domesticdog0_ group by domesticdog0_.name having count(domesticdog0_.id)>1

select domesticcat0_.name as col_0_0_ from DomesticCat domesticcat0_ group by domesticcat0_.name having count(domesticcat0_.id)>1

It returns only : "Buddy" and "Smokey". But it does not return "Max" wich is the name of a cat and a dog.