Portals in the Nether are linking to a new portal

What I expected to happen was...:
I was expecting to get to the portal (in the overworld) that I created, after going back through the portal (in the nether).

What actually happened was...:
Instead, a new portal in the overworld was generated.

Steps to Reproduce:
1. Create portal and go to the nether.
2. Then go back using the portal that was just created.
3. Realize that there is a new portal in the overworld.
4. If the bug doesn't show up, find another position and start at 1.