1.- Succesfully created my first nether portal.
2.- Enter the nether normally
3.- Portal on the nether side shut off after a ghast fired close to it. No way out, only dying.
4.- Died and respawn on the overworld.
5.- The nether portal on the overworld side was on (remember the other side was off when I died).
6.- Entered the nether and found it created a new active portal 2 blocks in front of the original that was still inactive. (See attached image.)