Not really an error, more like a consistency issue. Some titles are listed with “Episode 1” and some with “Episode I”. Maybe standardize them one way or the other, or a search alias at the very least?
This was fixed a while back. Did you try updating from Core?
I was adding series to my collection from Core. There was nothing existing in my database to update.
Seeing two results with “1” and the majority when using “I” as part of the search.