This was incorrect; Dimension 20 is a single series, with Fantasy High as Season 1 and Escape from the Bloodkeep as Season 2 (plus the just-started Unsleeping City as Season 3).
I have confirmed this fact with the network/studio in an email chain I can reproduce if requested.
I have copied all information from Escape from the Bloodkeep to the Fantasy High series (because I believe that will be the easiest way to fix the database), putting the episodes in Season 02, as the studio confirmed was correct. I have been careful to copy all the information, including actors, any translations (there weren't any), directors, et cetera.
Now, I just need to clean up the database- which requires moderator permissions. So I just need someone with the privileges to do the following two things:
- Delete the redundant series Dimension 20 - Escape from the Bloodkeep from the database.
- Rename the series Dimension 20 - Fantasy High to just "Dimension 20", as is correct. (the tag for the series is also just "fantasy-high", so it should be changed to "dimension-20" if possible)
(I don't believe I've done anything wrong, but if I have, please tell me so I can not do it in the future)