TYPO3 Flow configuration merging

I have 2 packages loaded in order of Package A then Package B. Both have setting of doctrine eventListener as below:

Package A Setting
-----------------

TYPO3:
  Flow:
    persistence:
      doctrine:
        eventListeners:
          -
            events: ['postRemove']
            listener: 'My\PackageA\Domain\EventListener\MyPackageAEventListener'

Package B Setting
-----------------

TYPO3:
  Flow:
    persistence:
      doctrine:
        eventListeners:
          -
            events: ['postLoad', 'postPersist', 'preFlush', 'onFlush', 'loadClassMetadata']
            listener: 'My\PackageB\Domain\EventListener\MyPackageBEventListener'

Then I run: ./flow configuration:show --type Settings --path TYPO3.Flow.persistence.doctrine.eventListeners
What I get is:

-
    events:
        - postLoad
        - postPersist
        - preFlush
        - onFlush
        - loadClassMetadata
    listener: My\PackageB\Domain\EventListener\MyPackageBEventListener

Is that the expected behaviour?

The reason for this is that all package settings get merged. Your examples translate to

array(..., 'eventListeners' => array(0 => 'events' => array('postRemove', ...)...)

and

array(..., 'eventListeners' => array(0 => 'events' => array('postLoad', ...)...)

note the two indexes 0, the second one will override the first one.
We should avoid using arrays in yaml and go for dictionaries instead:

TYPO3:
  Flow:
    persistence:
      doctrine:
        eventListeners:
          'MyPackageAEventListener'
            events: ['postRemove']
            listener: 'My\PackageA\Domain\EventListener\MyPackageAEventListener'

Now you can override the eventListener explicitly (using the 'MyPackageAEventListener' key) or append a new one, using its own key.