Every time anyone tries to make a portal in the Overworld and there is already one existing in the nether, the portals immediately link (even if they are hundreds of blocks apart. This makes it nearly impossible to create a nether hub.
Comments 2
Nether portal linkage is quite complex, please read up on it here: https://minecraft.gamepedia.com/Nether_portal#Portal_linkage_between_Overworld_and_Nether
This is intentional.
Can confirm having the same issue.
1) 0 / -1000
2) -700 / -520
3) 305 / -654
All lead to the same portal in the Nether.