Same problem with having different object references. Using the storage will be of no use given that entities in `$existing` come from a different query. This is basically a problem with our ORM 'personality', I decided early for not having a 'unit of work' that would uniquely register entities by their type and primary keys, that saved us quite a bit of work, but also requires us to do stuff like this. It is not to late to revert that decision, though.