Nezer's portals are not working correctly.
This problem has been present for a very long time. And I was surprised that it hasn't been fixed yet.
Bug:
When you create a portal at coordinates 1 ~ 1. And then you create another portal at coordinates -500 ~ -500. 2 portal is linked to 1 portal, although another portal in hell should be created.
How to create a bug:
-You enter the world, create a portal at coordinates 1 ~ 1, and a portal is created in hell, at the same coordinates.
Then, you teleport to the upper world at coordinates -500~ -500, and create a portal to hell.

• What should happen:
  You are creating 2 portals in hell, at the same coordinates.
• What's going on:
  You have 2 portals, linked to 1 portal.