I'm currently on v0.16.1
Yes, it is still happening. Or perhaps maybe we should be opening a different Jira entry as the problem I reported is slightly different (has nothing to do with animals but it does have to do with items disappearing and being replaced by other items). The problem occurred twice yesterday evening.
I'm currently on v0.16.1. I was online on my realm last night and my sword all of a sudden became a pickaxe. This happened twice. Both times I was standing in front of a bunch of zombies killing them (gotta love mob spawners). The first time my sword might have worn out and broke, but instead of having no sword, all of a sudden I had a duplicate of the item I had in my second slot. The next time it happened (also last night) my sword did not break (wasn't even close).
I no longer attempt to enchant weapons.
I have to admit though, a few days ago when my enchanted diamond pickaxe that was in my 2nd slot, that when it became duplicated I was not unhappy about it.
I have experienced this many times while attacking mobs. I'll kill a mob with my diamond enchanted sword (in slot 1) (or whatever weapon I currently have at the time) and all of a sudden my sword with 95% health is gone and I have a duplicate of the item that was in slot 2. This has happened many times.
I am not dropping the weapon because I have set the key mapping for dropping an item to the NumPad 9 which I never even get close to touching. Plus the weapon is no where to be found AND I have a duplicate of the item I had in the next slot.
I am running Windows 10 Beta v0.16.0, connected to a 6 month realm subscription I recently purchased. I am running on a Dell Precision 5510 laptop, i7-6820HQ CPU @ 2.70 Ghz, 16 GB of RAM, 64-bit Windows 10 Enterprise.
It isn't so bad when it clones your brand new super enchanted diamond pickaxe, but it sure bites the rest of the time. It would be nice to carry around a nice sword but for now, it is a waste of materials and enchanting levels.