Glad you got it. I'll post the following even though you already have it resolved.
If necessary, you can start over with your Opera profiles and Opera Sync and save as much as possible:
In both Operas, goto the URL opera://settings/passwords, click the 3 vertical dots to the right of "saved passwords" and export your passwords to a csv file. You can then edit each csv file with a text editor to remove any entries you want.
In both Opera, if you need to save your opened tabs, right-click on a tab in the tab bar, goto "save", and choose "all tabs as a speed dial folder". Repeat for any other workspaces you're using in Opera.
In both Operas, goto the URL opera://bookmarks, and use the drop-down at the bottom left to export your bookmarks (it will export the "speed dial" bookmarks folder too).
In both Operas, goto the URL opera://about and take note of "profile" and "cache" paths. Then, close Opera and rename those folders.
In another browser, log into https://www.sync.opera.com/ with each Opera account and choose "reset password" to wipe out all your sync data on the server for each account. (It won't reset your Opera account password or anything like that.)
In both Operas, goto the URL opera://bookmarks and import the bookmarks file you exported earlier. Then, on the start page, right-click on each speed dial folder you created to save your opened tabs and choose "open all in tabs" (making sure you're in the right workspace (that you'll have to recreate first) before doing so if you make use over workspaces.
In both Opera. Goto the URL opera://flags/#PasswordImport, enable the import flag, restart Opera, goto the URL opera://settings/passwords, click the 3 vertical dots to the right of "saved passwords" and choose to import the password csv file you previously exported. If the import flag is not present in opera://flags, goto the URL opera://flags/#temporary-unexpire-flags-m92, enable the flag, and restart Opera. Then, the import flag should show up (for the time being).
Then, you just have to readjust your settings and reinstall your extensions in both Operas.
Then, you can enable sync in both Operas. Make sure you use the right account in each Opera and make sure to only choose the things you actually want to sync.