Naturally Spawning Mobs Spawn inside each other

When I look around the world, I will often come across cows and sheep, all alone by themselves. When I punch them however, they turn into 3-5 cows/sheep. I've only seen this in cows and sheep, it appears naturally spawning mobs aren't spreading out. (They spawn 3 in one place rather than in 3 different spots.) I've included a short video of this happening.