horses leather armor duplication

So i was on my minecraft world , as usal (creative mode), and i was testing stuff
so i tame a horse (dont really know why to be honest) and i gave him a black leather armor for horses
then , (once again dont know why) kill him with potion of instant damage
and i saw that he drop 3 black leather amor for horses !
that is not a big issues but still a bug so immediatly reported it
hope you can fix that !