In the overworld (1.16.1) I created a new nether portal at an ocean monument which wasn't too far from an existing portal at a stronghold. I expected that these two portals would share one destination portal in the Nether because of their proximity to each other.
The first time I went through the new ocean monument portal, I did end up at the stronghold's destination portal in the Nether (coords: 222 115 -244). But the second time I went through the new ocean monument portal, the game created a new portal in the Nether at 233 90 -410.
Of course it is better to have two separate destination portals in the Nether and I had planned on manually making one if the game didn't create a separate portal, so all is good. I just found it odd that the game was inconsistent in this regard.
It's hard to tell without the coordinates of the Overworld portals but it would seem that they are close to the maximum separation that will allow them to share a destination portal in the Nether.
My guess would be that one side, left/right not front/back, of the ocean monument portal was just close enough to send you to the original portal in the Nether but the other side was just out of range and so when you went through it it created a new portal.
In theory it would be possible for the two sides to continue to send you to different portals in the Nether but now that there are 2 portals I expect that the new one would be closer to its optimal position and so both sides of the ocean monument portal will probably send you to new portal from now on (unless you disable the new portal in the Nether.)
Of course it could have been a glitch but I'd guess that it's normal portal mechanics.
In the overworld (1.16.1) I created a new nether portal at an ocean monument which wasn't too far from an existing portal at a stronghold. I expected that these two portals would share one destination portal in the Nether because of their proximity to each other.
The first time I went through the new ocean monument portal, I did end up at the stronghold's destination portal in the Nether (coords: 222 115 -244). But the second time I went through the new ocean monument portal, the game created a new portal in the Nether at 233 90 -410.
Of course it is better to have two separate destination portals in the Nether and I had planned on manually making one if the game didn't create a separate portal, so all is good. I just found it odd that the game was inconsistent in this regard.
It's hard to tell without the coordinates of the Overworld portals but it would seem that they are close to the maximum separation that will allow them to share a destination portal in the Nether.
My guess would be that one side, left/right not front/back, of the ocean monument portal was just close enough to send you to the original portal in the Nether but the other side was just out of range and so when you went through it it created a new portal.
In theory it would be possible for the two sides to continue to send you to different portals in the Nether but now that there are 2 portals I expect that the new one would be closer to its optimal position and so both sides of the ocean monument portal will probably send you to new portal from now on (unless you disable the new portal in the Nether.)
Of course it could have been a glitch but I'd guess that it's normal portal mechanics.
Just testing.