Confirming this for 1.9. In my case, the problem appeared after I updated the map from 1.8, on my multiplayer server. Chunks are slow at loading, especially if I tp to a region badly affected by duplicate entities, but I don't know if those problems are related. Affecting passive mobs cows, pigs, chicken, horses, villager and iron golem. So far.
Confirming this for 1.9. In my case, the problem appeared after I updated the map from 1.8, on my multiplayer server.
Chunks are slow at loading, especially if I tp to a region badly affected by duplicate entities, but I don't know if those problems are related.
Affecting passive mobs cows, pigs, chicken, horses, villager and iron golem. So far.