I am on a realm with my friends. One of them spawned a wither in the end dimension and didn't kill it. I didn't know this and I went into the end to create a farm, but I ended up killing it. I made the farm and left to the overworld. When I came back into the end, there was another wither there. It took 6 times of killing the wither before I realized there weren't multiple, because every time I killed it, there were no more, I even flew over the void just to make sure. Every time I either left the game, or just the dimension, there would be another wither with the exact same amount of health in its health bar (not full), and in the exact same spot (about 20 blocks out over the void). I have killed the same wither 13 times at this point and it's pretty annoying, is there anything you can do?

Thanks,

Sam