Hello, and I apologize for the late reply.
Because one change on one PC happens on all PCs, I believe it's a good idea to just start over on the sync process.
To start, please make sure turn off the important file backup on your old laptop, for all folders listed. You can do this by right clicking the OneDrive cloud icon on the taskbar, selecting "Settings" in the flyout, and then it should be the first option. Then, once it turns off, quit the OneDrive app (or alternatively, pause syncing for 24 hours). Open File Explorer on the same laptop. Open your OneDrive folder located in your user directory and type *- Copy.* into the search bar. This will show you all the files that have copy in their name, which should be the duplicates. It may take a while to search. Then, delete the duplicates, keeping the originals. On the new computer, delete both the files that were copied as well as the files that you moved via Ethernet. Or place them in a separate folder so in case you do something wrong, you can go back to them. Then, turn important file backup off on your new laptop, and quit OneDrive.
After you go through this process, on the old computer, make sure all files are marked as "Always available offline", and then unlink your old Microsoft account from OneDrive. Now, sign into your new Microsoft account. When asked to select a path, use the old path that was left behind by the old account. Then, make sure that all the files are synced to the cloud. You can check this by hovering over the OneDrive cloud icon on the taskbar. Once it's done, turn on important file backup again on all folders, on the old computer.
Once you have made sure that the files are all synced, turn on important file sync on your new computer. Watch the sync to make sure that the files aren't copied in a janky way again.
See if that fixes your issue. I hope to hear back from you.