New portals on Overworld are not creating a new location in Nether and an additional glitch is creating a separate return portal on the overworld

In an attempt to gain a better nether location we removed our original portal (505,82,-160) and created portal (275,-57,-70).

Not only was the Nether portal in the same location but upon returning to the over world it created a separate portal at (576,69,-220) thinking it was odd we attempted a second time and it again created another return portal (580,69,-220). Damaging a dock roof both times.

We decided to try a different method, finishing a ruined portal (661,74,-371). It again took us to the same nether location and again resulted in a separate return portal (593,63,-219) this time damaging the dock floor.

The process also obviously gave us additional obsidian