If the second level of the Pit is Choron’s Demise and you spawn a portal there then die fighting the boss, it will generally respawn you back on the first level, making you go through the portal back to Choron’s Demise and then run all the way back to the boss portal.
This may not be 100% universal, but for me it’s about 90% of the time that the boss portal spawns on Choron’s Demise, it’ll send me back to the first level if I die. It’s more an annoyance than anything, but if the second portal is spawned late in the second level, it can be up to a minute or so of running to get back to it, which is time lost unfairly.