I got the quest , went and robbed the first conch, then a long time later went back into the Old City area and found the second conch, but could only place one conch in the temple door.

Then I thought I should perhaps go to the guy who gives the quest, but he just took the one conch after a forced comment about having to fight (I didn't) to get it. After that I was only left with the one conch so obviously I'm not getting through the temple door.

Other than reloading and redoing everything I did today, is there a way around this? Is the temple loot worth worrying about?

Very annoying.

Also sorry if this topic has been discussed but the search function does not work. Neither does the Edit function here!

Hmm... I found one conch in the Old City before accepting the quest. After getting the quest I got the other one from the guy who had it (he happily gave it to my moon godlike for free, since she is "one of Ondra's chosen" :D )

I too was told by the quest giver that "someone robbed" the conch owner (certanly not me lol). But then I could place both conches in the door without any problems =/

Behind the door you find a pollaxe and a shield.
https://pillarsofeternity.gamepedia.com/Cadhu_Scalth
https://pillarsofeternity.gamepedia.com/Wahai_P%C5%8Draga

Unless you need them desperately or unless you're a completionist, you can skip.

(Just to make sure, you mean the door next to the mosaic, behind the giant grub, right? For any other doors, you need only one conch, you only need both for that one)

Edit to fix broken liks -_-

Thanks. In the end I restarted the entire quest and it worked this time...not sure how I messed up last time.