I've run into this same issue repeatedly across multiple machines, on Twine version 2.8.1. I wrote out a whole bug report before finding this existing one, so I'm going to copy paste in my bug description and my steps to reproduce.

Bug Description

I'm working on a twine 2 project in the web editor across two computers. When I finish work on one computer, I download the .twee file and upload it to my drive. Then I download it to the other computer and import the twee file.

I have copies of the project in the web editor's memory on both computers. When I attempt to import the newest version of the .twee into one of the computers, it says "A story with the same name in your library will be replaced." I check the box and click "Import."

It seems to work fine at first. But when I close the tab and reopen it, all the passages from the older version of the project, the one that should have been deleted, are loaded into the same twee file on top of the newer versions of the passages. This is honestly pretty catastrophic -- I've run into the issue after making many edits multiple times, and I've only been able to fix it by painstakingly removing the duplicate passages from the twee file in a text editor.

Steps to Reproduce

This is not unique to my active project. I created a test project in one web editor window, made several passages with placeholder text, and exported the twee file. Then I loaded the web editor in an incognito window, and imported the project. I made several edits in the incognito window, and exported the new twee.

When I imported the twee file on the original window, it seemed to work fine. But when I closed and opened the tab, it duplicated all the passages that were in the old version of the project. I've run through this process in both Firefox and Chrome, and the error occurred in both browsers.

Expected Behavior

Overwriting the old version of the project should completely erase the old version from memory and replace it with the new version. Right now its passages are being retained somewhere, and it's causing duplicate issues.

@jthyer thanks for resurrecting this bug! I can repro the problem in the web version but not the app version. This helps narrow down where the problem is. It is indeed annoying. I can't think of a workaround for it other than deleting the story before you re-import it, which is not great.

Excellent, thanks for taking a look! Yeah, deleting and reimporting works fine so it's not causing me any headaches now. I'm just glad the issue has eyes on it so more devs won't get blindsided in the future!