Thanks Yoshi, but... I meant something a little different.
As to the triggers, I meant the duplicate simple_triggers section in triggers file. I found fisheye's post where he said you can ignore it.
In the case with copied four-ways-inn, my problem was that I (foolishly) forgot to copy the .sco file in SceneObjects, and thus, though the menu showed me the correct scene, it was empty because M&B couldn't read the scene data.
For a change, I used the renamed zendar tavern scene, copied the respective .sco, and got another bug: when I entered my modified four-winds-inn, I saw the six Swadian knights who were supposed to be garrisoning it! However this is the first time I saw the defenders showing up not in battle. Weird, imagine six unarmed and dismounted Swadian knights lined up against a wall in zendar tavern (two were standing on a table)! I even could talk to them! However it was only the default "Tell me about yourself" conversation.