Import finds existing series

Sonarr version (exact version):
Mono version (if Sonarr is not running on Windows):
OS: Windows 10 x64 20H2
Debug logs:
(Make sure debug logging is enabled in settings and post the full log to hastebin/pastebin/dropbox/google drive or something similar, do not post them directly here. Post in .txt not .doc, .rtf or some other formatted document)
Description of issue:
I have folders created in my Sonarr root folder for all my TV series including some series that are in pre-production or are rumoured to be in development and not listed on I use Series>Import to search for these series to see if there is any release date yet and add them if there is.
For about the last two or three weeks, when I use Series>Import, Sonarr does list the names of these pre-production/in-development series but it is now also listing some of my existing saved series that are airing or have future release dates or series I have previously added ie are listed on, eg Amazing Stories, Avatar:The Last Airbender, Foundation, etc.
Prior to three weeks ago, Series>Import would only list series that I had not previously added (and had folders set up obviously).

In the debug log, out of the 45 unmapped folders, I estimate it finds 15 series that I previously have added to my list. I have a list of 92 TV series so it does not list every TV series I previously added. Sonarr lists the same 15 series that I had previously added, each time import is used.

Edit:Ok, I think I found the problem.
eg Amazing Stories, my folder is called Amazing Stories but the TV series is titled Amazing Stories (2020). Once I renamed my folder to Amazing Stories (2020), this TV series no longer appears in the Series>Import list. Similarly with Foundation after renaming my folder to Foundation (2021)

Thank you.