SpringData r2dbc vs jpa when saving a list of entities with the same ids

Question

In Jpa Spring Data when using saveAll for entities with the same ids - saveAll successfully saves all the enitities into the database. For example

public interface JpaRepository extends JpaRepository<Entity, String> {}
...
... 
Entity entity1 = Entity.build()
.version(1L)
.id(123)
.status("NEW")
.build;
...
Entity entity2 = Entity.build()
.version(1L)         <---- has the same version as in entity1 
.id(123)             <---- has the same id as in entity1 
.status("IN_PROGRESS")
.build;
...
...
jpaRepository.saveAll(List.of(entity1, entity2));
 

This jpaRepository.saveAll(List.of(entity1, entity2)) works successfully with no issues. The result of operation will be the record with version=2L and status="IN_PROGRESS".

If we use r2dbc repository:

public interface R2dbcRepository extends ReactiveCrudRepository<Entity, String><Entity, String> {}
...
r2dbcRepository.saveAll(List.of(entity1, entity2)).blockLast();

The operation of r2dbcRepository.saveAll(List.of(entity1, entity2)).blockLast() fails with an exception:

Failed to update table [entity]; Version does not match for row with Id [123] org.springframework.dao.OptimisticLockingFailureException: Failed to update table [entity]; Version does not match for row with Id [123] at org.springframework.data.r2dbc.core.R2dbcEntityTemplate.lambda$doUpdate$12(R2dbcEntityTemplate.java:637)

Why those JpaRepository and R2dbcRepository repositories works differently when saving a list of entities with the same ids? Is there any documentation how they treat entities with the same ids in saveAll operation.

---

Java 21.0.2; SpringBoot 3.2.2; postgresql 42.2.4; r2dbc 1.0.7.RELEASE