Unusual Bunny name in Vanilla, assumed failed Killer Bunny spawn.

I found this rabbit here named entity.KillerRabbit.name amongst a heard of very similar rabbits in my minecraft vanilla survival world. Despite his name, he was not aggressive and seemed to be completely normal, besides the obvious difference.

As for triggering this bug again, I've no idea how to go about it, and I assume it was a failed attempt to spawn a killer rabbit.