Portals not linked at all even though no third party tools were ever used.

I run a realm on Minecraft Bedrock. Me and my friends started the world basically a month ago and have only used creative to work on spawn. Two days before the nether update released, we opened the realm to a bunch of people. Before the nether update released, no one has been to the nether nor have we used third party tools to modify or reset the nether. But when one portal is created, it links to someone else's portal in the nether despite them being hundreds of blocks away. The nether portal that is being linked to the others inside the nether teleports players to an acacia biome nowhere near where other portals have been placed. As I said, no third party tools nor world edit have been used so the reason why this is happening is beyond my comprehension. I don't know if it has to do with the world itself but me and my friends have made considerable progress on the realm and would hate to lose it.