Minecraft spider called spider (2)?

I just farmed on surgery addiction in the farm world it was night and I came across a spider named Spider (2) when I killed it spawned right where I killed you and then came a zombie named Zombie (2) and the same thing happened. Can someone clarify I'm still new to surgery addiction?

You can find this on many servers, for example there are always 2 zombies that work as you described it. The first one is killed and then the second spawns.

And why is it that you die and lose your things?

I just don't know that for more loot I think