It’s hard to tell from the information you provided.
But I have shows that were US, UK, and AU versions.
If they are named correctly Plex usually doesn’t have an issue with it.
BUT… since the API Version change at the TVDB I’ve found lots of issues. seems they changed database information also. Found shows that have seasons combined into one. There are dates for shows created and aired decades ago that now have current dates.
Best thing to do is go to thetvdb lookup the shows and make sure your titles match so it can get pulled correctly. EVEN if you know that their information is not correct. If you want to go the route of trying to get them to fix it, more power to you. Let me know how it works out.
Yes I realized that last night when I took a closer look and noticed that the US episode is showing up in the original (I’m assuming UK, w/o suffix) show.
In fairness, it just aired, so maybe they’ll get to it.
I’ve been struggling with this as well, glad to see its not just me. I’ve tried the same folder structure as OP, added the year to each one, edited the file name to include the show name and year. Nothing worked. Makes sense if its an API thing on TheTVDB, but weird that they list them correctly on their site, hopefully they fix it soon.