There are no assertions, invariants, or errors thrown in DatabaseImpl::createCollection if a collection is created using the UUID of a collection that already exists in the UUIDCatalog.

Creating a new collection with an existing UUID results in the UUIDCatalog::onCreateCollection observer removing the entry of the previous collection. This allows two collections to exist with the same UUID. In the case of two-phase collection drops, this can result in no collections registered to a UUID, despite existing.