I have two portals in the nether that are close by that now since the pre-release both over-world locations teleport to the same portal in the nether, which wasn't the case before the pre-releases came out.
ex. (from the nether) X goes to X and back, Z goes to Z but comes back to X(Z)
Overworld Z---------------------------------------------X
Nether Z------------X(Z)
Thank you.
Portal linking logic was not changed in 1.16, please read the wiki article as linking is quite complex: https://minecraft.gamepedia.com/Nether_portal#Portal_linkage_between_Overworld_and_Nether